Publications T. Helgaker



Publication list

1977
1980 1981 1982 1984 1986 1987 1988 1989
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
2010 2011 2012 2013
    1977

  1. Leo Tolstoj: Om vold og kjærlighet (Zakon nasilija i zakon ljubvi),
    T. U. Helgaker,
    translation from Russian with introduction, Solum, Oslo 1977

  2. Boris Pilnjak: Armesjefens død (Povest’ nepogasjennoj luny),
    T. U. Helgaker,
    translation from Russian, in Moderne russiske fortellere, ed. G. Kjetsaa (Aschehoug, Oslo 1977), pp. 84–119

    1980

  3. Strukturundersøkelser av enkle dialkylsinkforbindelser,
    T. U. Helgaker,
    master thesis, (Department of Chemistry, University of Oslo, 1980)

    1981

  4. Basis set considerations for the calculation of gradients in the LCAO formalism,
    J. Almlöf and T. Helgaker,
    Chem. Phys. Lett. 83, 125–128 (1981)

    1982

  5. Simple derivation of the potential energy gradient for an arbitrary electronic wave function,
    T. U. Helgaker,
    Int. J. Quantum Chem. 21, 939–940 (1982)

  6. The molecular structures of dimethyl-, diethyl- and dipropylzinc determined by gas phase electron diffraction. Normal coordinate analysis and ab initio molecular orbital calculations on dimethylzinc,
    A. Almenningen, T. U. Helgaker, A. Haaland, and S. Samdal,
    Acta Chem. Scand. A36, 159–166 (1982)

    1984

  7. A second-quantization approach to the analytical evaluation of response properties for perturbation-dependent basis sets,
    T. U. Helgaker and J. Almlöf,
    Int. J. Quantum Chem. 26, 275–291 (1984)

  8. Higher molecular-deformation derivatives of the configuration-interaction energy,
    J. Simons, P. Jørgensen, and T. U. Helgaker,
    Chem. Phys. 86, 413–432 (1984)

    1986

  9. Hamiltonian expansion in geometrical distortions,
    T. U. Helgaker,
    in Geometrical Derivatives of Energy Surfaces and Molecular Properties,
    P. Jørgensen and J. Simons, eds. (Reidel, Dordrecht, 1986), pp. 1–6

  10. Calculation of dipole moments, polarizabilities and their geometrical derivatives,
    T. U. Helgaker,
    in Geometrical Derivatives of Energy Surfaces and Molecular Properties,
    P. Jørgensen and J. Simons, eds. (Reidel, Dordrecht, 1986), pp. 115–133

  11. Walking on MCSCF potential energy surfaces: Application to H2O2 and NH3,
    D. L. Yeager, H. J. Aa. Jensen, P. Jørgensen, and T. U. Helgaker,
    in Geometrical Derivatives of Energy Surfaces and Molecular Properties,
    P. Jørgensen and J. Simons, eds. (Reidel, Dordrecht, 1986), pp. 229–241

  12. Molecular Hessians for large-scale MCSCF wave functions,
    T. U. Helgaker, J. Almlöf, H. J. Aa. Jensen, and P. Jørgensen,
    J. Chem. Phys. 84, 6266–6279 (1986)

  13. Analytical calculation of MCSCF dipole-moment derivatives,
    T. U. Helgaker, H. J. Aa. Jensen, and P. Jørgensen,
    J. Chem. Phys. 84, 6280–6284 (1986)

  14. Systematic determination of MCSCF equilibrium and transition structures and reaction paths,
    H. J. Aa. Jensen, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 85, 3917–3929 (1986)

  15. Development of quantum chemical methods for analytical calculation of molecular properties,
    T. U. Helgaker,
    dr. philos. thesis, (Department of Chemistry, University of Oslo, 1986)

    1987

  16. The ground-state potential energy surface of diazene,
    H. J. Aa. Jensen, P. Jørgensen, and T. Helgaker,
    J. Am. Chem. Soc. 109, 2895–2901 (1987)

    1988

  17. A gradient extremal walking algorithm,
    P. Jørgensen, H. J. Aa. Jensen, and T. Helgaker,
    Theor. Chim. Acta 73, 55–65 (1988)

  18. Gaussian basis sets for high-quality ab initio calculations,
    J. Almlöf, T. Helgaker, and P. R. Taylor,
    J. Phys. Chem. 92, 3029–3033 (1988)

  19. Analytical calculation of geometrical derivatives in molecular electronic structure theory,
    T. Helgaker and P. Jørgensen,
    Adv. Quantum Chem. 19, 183–245 (1988)

  20. Effect of the crystalline environment on molecular geometries–an ab initio study of cyanamide,
    T. U. Helgaker and B. Klewe,
    Acta Chem. Scand. A42, 269–272 (1988)

  21. Møller–Plesset energy derivatives,
    P. Jørgensen and T. Helgaker,
    J. Chem. Phys. 89, 1560–1570 (1988)

  22. Translational and rotational symmetries of molecular geometrical derivatives,
    T. Helgaker,
    Acta Chem. Scand. A42, 515–518 (1988)

  23. A multiconfigurational self-consistent reaction-field method,
    K. V. Mikkelsen, H. Ågren, H. J. Aa. Jensen, and T. Helgaker,
    J. Chem. Phys. 89, 3086–3095 (1988)

  24. Molecular wave functions and properties calculated using floating Gaussian orbitals,
    T. Helgaker and J. Almlöf,
    J. Chem. Phys. 89, 4889–4902 (1988)

    1989

  25. Configuration-interaction energy derivatives in a fully variational formulation,
    T. Helgaker and P. Jørgensen,
    Theor. Chim. Acta 75, 111–127 (1989)

  26. A numerically stable procedure for calculating Møller–Plesset energy derivatives, derived using the theory of Lagrangians,
    T. Helgaker, P. Jørgensen, and N. C. Handy,
    Theor. Chim. Acta 76, 227–245 (1989)

  27. Accurate calculations of the dynamic dipole polarizability of N2. A multiconfigurational linear response study using restricted active space (RAS) wavefunctions,
    H. J. Aa. Jensen, P. Jørgensen, T. Helgaker, and J. Olsen,
    Chem. Phys. Lett. 162, 355–360 (1989)

  28. Applications of second order MCSCF on electronic structures, reactions and spectra of molecules,
    H. Ågren, H. J. Aa. Jensen, T. Helgaker, P. Jørgensen, and J. Olsen,
    Annales de la Société Scientifique de Bruxelles 103, 149–181 (1989)

    1990

  29. Coupled cluster energy derivatives. Analytic Hessian for the closed-shell coupled cluster singles and doubles wave function: Theory and applications,
    H. Koch, H. J. Aa. Jensen, P. Jørgensen, T. Helgaker, G. E. Scuseria, and H. F. Schaefer III,
    J. Chem. Phys. 92, 4924–4940 (1990)

  30. Excitation energies from the coupled-cluster singles and doubles linear response function (CCSDLR). Applications to Be, CH+, CO, and H2O,
    H. Koch, H. J. Aa. Jensen, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 93, 3345–3350 (1990)

  31. Integration of the classical equations of motion on ab initio molecular potential energy surfaces using gradients and Hessians: application to translational energy release upon fragmentation,
    T. Helgaker, E. Uggerud, and H. J. Aa. Jensen,
    Chem. Phys. Lett. 173, 145–150 (1990)

    1991

  32. Transition-state optimizations by trust-region image minimization,
    T. Helgaker,
    Chem. Phys. Lett. 182, 503–510 (1991)

  33. An electronic Hamiltonian for origin independent calculations of magnetic properties,
    T. Helgaker and P. Jørgensen,
    J. Chem. Phys. 95, 2595–2601 (1991)

  34. Excited state structures and vibronic spectra of H2CO+, HDCO+, and D2CO+ using molecular gradient and Hessian techniques,
    A. Cesar, H. Ågren, T. Helgaker, P. Jørgensen, and H. J. Aa. Jensen,
    J. Chem. Phys. 95, 5906–5917 (1991)

  35. An ab initio investigation of the potential energy function and rotation–vibration energies of H2O·Na+,
    V. Špirko, N. M. Daadoch, H. J. Aa. Jensen, P. Jørgensen, and T. Helgaker,
    Chem. Phys. Lett. 185, 265–269 (1991)

    1992

  36. Spin–orbit coupling constants in a multiconfiguration linear response approach,
    O. Vahtras, H. Ågren, P. Jørgensen, H. J. Aa. Jensen, T. Helgaker, and J. Olsen,
    J. Chem. Phys. 96, 2118–2126 (1992)

  37. The second-order energy contribution from the spin–orbit interaction operator to the potential energy curve of Cr2,
    O. Vahtras, H. Ågren, P. Jørgensen, H. J. Aa. Jensen, and T. Helgaker,
    Intern. J. Quantum Chem. 41, 729–731 (1992)

  38. Indirect nuclear spin–spin coupling constants from multiconfiguration linear response theory,
    O. Vahtras, H. Ågren, P. Jørgensen, H. J. Aa. Jensen, S. B. Padkjær, and T. Helgaker,
    J. Chem. Phys. 96, 6120–6125 (1992)

  39. The magnetic hyperpolarizability anisotropy of the neon atom,
    M. Jaszuński, H. J. Aa. Jensen, P. Jørgensen, A. Rizzo, T. Helgaker, and K. Ruud,
    Chem. Phys. Lett. 191, 599–602 (1992)

  40. Dynamics of the reaction CH2OH+ → CHO+ + H2. Translational energy release from ab initio trajectory calculations,
    E. Uggerud and T. Helgaker,
    J. Am. Chem. Soc. 114, 4265–4268 (1992)

  41. Calculation of geometrical derivatives in molecular electronic structure theory,
    T. Helgaker and P. Jørgensen,
    in Methods in Computational Molecular Physics,
    S. Wilson and G. H. F. Diercksen, eds. (Plenum, New York, 1992), pp. 353–421

  42. Optimization of minima and saddle points,
    T. Helgaker,
    in Lecture Notes in Quantum Chemistry,
    B. Roos, ed. (Springer, Berlin, 1992), pp. 295–324

  43. On the evaluation of derivatives of Gaussian integrals,
    T. Helgaker and P. R. Taylor,
    Theor. Chim. Acta 83, 177–183 (1992)

  44. The hydrogen atom in crossed static electromagnetic and non-resonant laser fields,
    T. Helgaker and I. Tomashevsky,
    Phys. Scr. 46, 354–356 (1992)

  45. Interconversion of diborane (4) isomers,
    J. F. Stanton, J. Gauss, R. J. Bartlett, T. Helgaker, P. Jørgensen, H. J. Aa. Jensen, and P. R. Taylor,
    J. Chem. Phys. 97, 1211–1216 (1992)

  46. Spin polarization in restricted electronic structure theory: Multiconfiguration self-consistent-field calculations of hyperfine coupling constants,
    B. Fernandez, P. Jørgensen, J. Byberg, J. Olsen, T. Helgaker, and H. J. Aa. Jensen,
    J. Chem. Phys. 97, 3412–3419 (1992)

  47. First-order nonadiabatic coupling matrix elements from multiconfigurational self-consistent-field response theory,
    K. L. Bak, P. Jørgensen, H. J. Aa. Jensen, J. Olsen, and T. Helgaker,
    J. Chem. Phys. 97, 7573–7584 (1992)

  48. Multiconfigurational quadratic response functions for singlet and triplet perturbations: The phosphorescence lifetime of formaldehyde
    O. Vahtras, H. Ågren, P. Jørgensen, H. J. Aa. Jensen, T. Helgaker, and J. Olsen,
    J. Chem. Phys. 97, 9178–9187 (1992)

    1993

  49. Nuclear magnetic shielding tensor for the ethylenic carbon atom in tetrachlorocyclopropene,
    M. Jaszuński, K. L. Bak, P. Jørgensen, T. Helgaker, K. Ruud, and H. J. Aa. Jensen,
    Chem. Phys. Lett. 204, 608–610 (1993)

  50. Large scale random phase calculations for direct self-consistent field wavefunctions,
    H. Koch, H. Ågren, P. Jørgensen, T. Helgaker, and H. J. Aa. Jensen,
    Chem. Phys. 172, 13–20 (1993)

  51. Direct atomic orbital based self-consistent-field calculations of nonlinear molecular properties. Application to the frequency dependent hyperpolarizability of para-nitroaniline,
    H. Ågren, O. Vahtras, H. Koch, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 98, 6417–6423 (1993)

  52. Frequency dependent hyperpolarizabilities of polyynes,
    M. Jaszuński, P. Jørgensen, H. Koch, H. Ågren, and T. Helgaker,
    J. Chem. Phys. 98, 7229–7235 (1993)

  53. Gauge-origin independent multiconfigurational self-consistent-field theory for vibrational circular dichroism,
    K. L. Bak, P. Jørgensen, T. Helgaker, K. Ruud, and H. J. Aa. Jensen,
    J. Chem. Phys. 98, 8873–8887 (1993)

  54. The nuclear spin–spin coupling in N2 and CO,
    O. Vahtras, H. Ågren, P. Jørgensen, T. Helgaker, and H. J. Aa. Jensen,
    Chem. Phys. Lett. 209, 201–206 (1993)

  55. Hartree–Fock limit magnetizabilities from London orbitals,
    K. Ruud, T. Helgaker, K. L. Bak, P. Jørgensen, and H. J. Aa. Jensen,
    J. Chem. Phys. 99, 3847–3859 (1993)

  56. Mechanism, energetics, kinetics and dynamics of the reaction C2H6+˙ → C2H4+˙ + H2,
    S. M. Bråten, T. Helgaker, E. Uggerud, and T. Vulpius,
    Org. Mass Spectrom. 28, 1262–1269 (1993)

  57. Ab initio study of the NMR shielding constants and spin–spin coupling constants in cyclopropene,
    A. Barszczewicz, M. Jaszuński, K. Kamieńska-Trela, T. Helgaker, P. Jørgensen, and O. Vahtras,
    Theor. Chim. Acta 87, 19–28 (1993)

    1994

  58. Frequency-dependent polarizabilities of O2 and van der Waals coefficients of dimers containing O2,
    H. Hettema, P. E. S. Wormer, P. Jørgensen, H. J. Aa. Jensen, and T. Helgaker,
    J. Chem. Phys. 100, 1297–1302 (1994)

  59. MCSCF calculations of nitrogen NMR shielding constants using London atomic orbitals,
    M. Jaszuński, T. Helgaker, K. Ruud, K. L. Bak, and P. Jørgensen,
    Chem. Phys. Lett. 220, 154–160 (1994)

  60. MCSCF calculations of Verdet constants,
    M. Jaszuński, P. Jørgensen, A. Rizzo, K. Ruud, and T. Helgaker
    Chem. Phys. Lett. 222, 263–266 (1994)

  61. Basis set convergence of atomic axial tensors obtained from self-consistent field calculations using London atomic orbitals,
    K. L. Bak, P. Jørgensen, T. Helgaker, K. Ruud, and H. J. Aa. Jensen,
    J. Chem. Phys. 100, 6620–6627 (1994)

  62. Multiconfigurational self-consistent field calculations of nuclear shieldings using London atomic orbitals,
    K. Ruud, T. Helgaker, R. Kobayashi, P. Jørgensen, K. L. Bak, and H. J. Aa. Jensen,
    J. Chem. Phys. 100, 8178–8185 (1994)

  63. Theoretical calculations of the magnetizability of some small fluorine-containing molecules using London atomic orbitals,
    K. Ruud, T. Helgaker, P. Jørgensen, and K. L. Bak,
    Chem. Phys. Lett. 223, 12–18 (1994)

  64. An ab initio nuclear magnetic resonance spectrum of vinyllithium,
    K. Ruud, T. Helgaker, P. Jørgensen, and K. L. Bak,
    Chem. Phys. Lett. 226, 1–10 (1994)

  65. A direct atomic orbital driven implementation of the coupled cluster singles and doubles (CCSD) model,
    H. Koch, O. Christiansen, R. Kobayashi, P. Jørgensen, and T. Helgaker,
    Chem. Phys. Lett. 228, 233–238 (1994)

  66. MCSCF reaction-path energetics and thermal rate-constants for the reaction of 3NH with H2,
    J. Ischtwan, P. Schwerdtfeger, S. D. Peyerimhoff, M. A. Collins, T. Helgaker, P. Jørgensen, and H. J. Aa. Jensen,
    Theor. Chim. Acta 89, 157–168 (1994)

  67. Multiconfigurational self-consistent field calculations of nuclear magnetic resonance indirect spin–spin coupling constants,
    A. Barszczewicz, T. Helgaker, M. Jaszuński, P. Jørgensen, and K. Ruud,
    J. Chem. Phys. 101, 6822–6828 (1994)

  68. Magnetizability of hydrocarbons,
    K. Ruud, H. Skaane, T. Helgaker, K. L. Bak, and P. Jørgensen,
    J. Am. Chem. Soc. 116, 10135–10140 (1994)

  69. The Vegard–Kaplan band and the phosphorescent decay of N2,
    J. Olsen, B. Minaev, O. Vahtras, H. Ågren, P. Jørgensen, H. J. Aa. Jensen, and T. Helgaker,
    Chem. Phys. Lett. 231, 387–394 (1994)

  70. Basis set convergence and correlation effects in vibrational circular dichroism calculations using London atomic orbitals,
    K. L. Bak, P. Jørgensen, T. Helgaker, and K. Ruud,
    Faraday Discuss. 99, 121–129 (1994)

  71. Vibrational Raman optical activity calculations using London atomic orbitals,
    T. Helgaker, K. Ruud, K. L. Bak, P. Jørgensen, and J. Olsen,
    Faraday Discuss. 99, 165–180 (1994)

    1995

  72. Orbital connections for perturbation-dependent basis sets,
    J. Olsen, K. L. Bak, K. Ruud, T. Helgaker, and P. Jørgensen,
    Theor. Chim. Acta 90, 421–439 (1995)

  73. Ab initio calculation of electronic circular dichroism for trans-cyclooctene using London atomic orbitals,
    K. L. Bak, Aa. E. Hansen, K. Ruud, T. Helgaker, J. Olsen, and P. Jørgensen,
    Theor. Chim. Acta 90, 441–458 (1995)

  74. A numerically stable orbital connection for the calculation of analytical Hessians using perturbation-dependent basis sets,
    K. Ruud, T. Helgaker, J. Olsen, P. Jørgensen, and K. L. Bak,
    Chem. Phys. Lett. 235, 47–52 (1995)

  75. Loss of H2 from CH3NH3+, CH3OH2+ and CH3FH+. Reaction mechanisms and dynamics from observation of metastable ion fragmentations and ab initio calculations,
    E. L. Øiestad, Å. M. L. Øiestad, H. Skaane, K. Ruud, T. Helgaker, E. Uggerud, and T. Vulpius,
    Eur. J. Mass Spectrom. 1, 121–129 (1995)

  76. NMR shielding tensors and indirect spin–spin coupling tensors in HCN, HNC, CH3CN, and CH3NC molecules,
    A. Barszczewicz, T. Helgaker, M. Jaszuński, P. Jørgensen, and K. Ruud,
    J. Magn. Reson. A 114, 212–218 (1995)

  77. Accurate magnetizabilities of the isoelectronic series BeH−, BH, and CH+. The MCSCF–GIAO approach,
    K. Ruud, T. Helgaker, K. L. Bak, P. Jørgensen, and J. Olsen,
    Chem. Phys. 195, 157–169 (1995)

  78. Electric field dependence of magnetic properties: Multiconfigurational self-consistent field calculations of hypermagnetizabilities and nuclear shielding polarizabilities of N2, C2H2, HCN, and H2O,
    A. Rizzo, T. Helgaker, K. Ruud, A. Barszczewicz, M. Jaszuński, and P. Jørgensen,
    J. Chem. Phys. 102, 8953–8966 (1995)

  79. Random-phase calculations of frequency-dependent polarizabilities and hyperpolarizabilities of long polyene chains,
    Y. Luo, H. Ågren, H. Koch, P. Jørgensen, and T. Helgaker,
    Phys. Rev. B 51, 14949–14957 (1995)

  80. SCF calculations of the NMR shielding tensor for the ethylenic carbon atom in C3Cl4,
    M. Jaszuński, T. Helgaker, K. Ruud, P. Jørgensen, K. L. Bak, and H. Koch,
    Mol. Phys. 85, 671–673 (1995)

  81. NMR properties of N3−. A comparison of theory and experiment,
    M. Jaszuński, S. Szymański, O. Christiansen, P. Jørgensen, T. Helgaker, and K. Ruud,
    Chem. Phys. Lett. 243, 144–150 (1995)

  82. Second-order methods for the optimization of molecular potential energy surfaces,
    T. Helgaker, K. Ruud, and P. R. Taylor,
    in The Reaction Path in Chemistry: Current Approaches and Perspectives,
    D. Heidrich, ed., (Kluwer, Dordrecht, 1995), pp. 109–136

  83. Gaussian basis sets and molecular integrals,
    T. Helgaker and P. R. Taylor,
    in Modern Electronic Structure Theory, Part II,
    D. R. Yarkony, ed., (World Scientific, Singapore, 1995), pp. 725–856

    1996

  84. Long-range effects of interatomic interactions on NMR shielding constants,
    A. Barszczewicz, M. Jaszuński, T. Helgaker, and K. Ruud,
    Chem. Phys. Lett. 250, 1–8 (1996)

  85. The integral-direct coupled cluster singles and doubles model,
    H. Koch, A. Sánchez de Merás, T. Helgaker, and O. Christiansen,
    J. Chem. Phys. 104, 4157–4165 (1996)

  86. Efficient parallel implementation of response theory: calculations of the second hyperpolarizability of polyacenes,
    P. Norman, D. Jonsson, H. Ågren, P. Dahle, K. Ruud, T. Helgaker, and H. Koch,
    Chem. Phys. Lett. 253, 1–7 (1996)

  87. Magnetizability and nuclear shielding constants of solvated water,
    K. V. Mikkelsen, K. Ruud, and T. Helgaker,
    Chem. Phys. Lett. 253, 443–447 (1996)

  88. The molecular structure of ferrocene,
    H. Koch, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 104, 9528–9530 (1996)

  89. MCSCF calculations of hypermagnetizabilities and nuclear shielding polarizabilities of CO and CH4,
    S. Coriani, A. Rizzo, K. Ruud, and T. Helgaker,
    Mol. Phys. 88, 931–947 (1996)

  90. Perturbation-dependent atomic orbitals for the calculation of spin–rotation constants and rotational g tensors,
    J. Gauss, K. Ruud, and T. Helgaker,
    J. Chem. Phys. 105, 2804–2812 (1996)

  91. Ab initio studies of the [AX]2 spin systems of cis- and trans-N2F2,
    M. Jaszuński, T. Helgaker, and K. Ruud,
    Magn. Reson. Chem. 34, 646–649 (1996)

  92. Energetics and dynamics of intermolecular proton-transfer processes. 2. Ab initio direct dynamics calculations of the reaction H3O+ + NH3 → NH4+ + H2O,
    H.-H. Bueker, T. Helgaker, K. Ruud, and E. Uggerud,
    J. Phys. Chem. 100, 15388–15392 (1996)

  93. Magnetizabilities and nuclear shielding constants of the fluoromethanes in the gas phase and solution,
    P.-O. Åstrand, K. V. Mikkelsen, K. Ruud, and T. Helgaker,
    J. Phys. Chem. 100, 19771–19782 (1996)

  94. Full CI calculations of the magnetizability and rotational g factor of the hydrogen molecule,
    K. Ruud, P.-O. Åstrand, T. Helgaker, and K. V. Mikkelsen,
    J. Mol. Struct.: THEOCHEM 388, 231–235 (1996)

  95. Integral direct calculation of CC2 excitation energies: singlet excited states of benzene,
    O. Christiansen, H. Koch, P. Jørgensen, and T. Helgaker,
    Chem. Phys. Lett. 263, 530–539 (1996)

  96. Large-scale calculations of excitation energies in coupled cluster theory: The singlet excited states of benzene,
    O. Christiansen, H. Koch, A. Halkier, P. Jørgensen, T. Helgaker, and A. Sánchez de Merás,
    J. Chem. Phys. 105, 6921–6939 (1996)

    1997

  97. Cotton–Mouton effect and shielding polarizabilities in ethylene: an MCSCF study,
    S. Coriani, A. Rizzo, K. Ruud, and T. Helgaker,
    Chem. Phys. 216, 53–66 (1997)

  98. The magnetizability, rotational g tensor, and quadrupole moment of PF3 revisited,
    K. Ruud and T. Helgaker,
    Chem. Phys. Lett. 264, 17–23 (1997)

  99. A multipole reaction-field model for gauge-origin independent magnetic properties of solvated molecules,
    K. V. Mikkelsen, P. Jørgensen, K. Ruud, and T. Helgaker,
    J. Chem. Phys. 106, 1170–1180 (1997)

  100. The CC3 model: An iterative coupled cluster approach including connected triples,
    H. Koch, O. Christiansen, P. Jørgensen, A. M. Sánchez de Merás, and T. Helgaker,
    J. Chem. Phys. 106, 1808–1818 (1997)

  101. Mechanisms, energetics and dynamics of a key reaction sequence during the decomposition of nitromethane: HNO + HNO → N2O + H2O,
    K. Ruud, T. Helgaker, and E. Uggerud,
    J. Mol. Struct.: THEOCHEM 393, 59–71 (1997)

  102. The prediction of molecular equilibrium structures by the standard electronic wave functions,
    T. Helgaker, J. Gauss, P. Jørgensen, and J. Olsen,
    J. Chem. Phys. 106, 6430–6440 (1997)

  103. The magnetizability anisotropy and rotational g factor of deuterium hydride and the deuterium molecule,
    P.-O. Åstrand, K. Ruud, K. V. Mikkelsen, and T. Helgaker,
    Chem. Phys. Lett. 271, 163–166 (1997)

  104. Ab initio calculation of the NMR shielding and indirect spin–spin coupling constants of fluoroethylene,
    T. Helgaker, M. Jaszuński, and K. Ruud,
    Mol. Phys. 91, 881–889 (1997)

  105. Principles of direct 4-component relativistic SCF: application to caesium auride,
    T. Saue, K. Fægri, T. Helgaker, and O. Gropen,
    Mol. Phys. 91, 937–950 (1997)

  106. Basis-set convergence of correlated calculations on water,
    T. Helgaker, W. Klopper, H. Koch, and J. Noga,
    J. Chem. Phys. 106, 9639–9646 (1997)

  107. First-order one-electron properties in the integral-direct coupled cluster singles and doubles model,
    A. Halkier, H. Koch, O. Christiansen, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 107, 849–866 (1997)

  108. The Cotton–Mouton effect of liquid water. Part I: The dielectric continuum model,
    K. Ruud, T. Helgaker, A. Rizzo, S. Coriani, and K. V. Mikkelsen,
    J. Chem. Phys. 107, 894–901 (1997)

  109. CCSDT calculations of molecular equilibrium geometries,
    A. Halkier, P. Jørgensen, J. Gauss, and T. Helgaker,
    Chem. Phys. Lett. 274, 235–241 (1997)

  110. Electric and magnetic properties of the nitroethene molecule,
    P.-O. Åstrand, K. Ruud, K. V. Mikkelsen, and T. Helgaker,
    Mol. Phys. 92, 89–96 (1997)

  111. A systematic ab initio study of the water dimer in hierarchies of basis sets and correlations models,
    A. Halkier, H. Koch, P. Jørgensen, O. Christiansen, I. M. Beck Nielsen, and T. Helgaker,
    Theor. Chem. Acc. 97, 150–157 (1997)

  112. Multiple basis sets in calculations of triples corrections in coupled-cluster theory,
    W. Klopper, J. Noga, H. Koch, and T. Helgaker,
    Theor. Chem. Acc. 97, 164–176 (1997)

  113. Extensive relativistic calculations on the palladium hydride molecule,
    M. Sjøvoll, H. Fagerli, O. Gropen, J. Almlöf, T. Saue, J. Olsen, and T. Helgaker,
    J. Chem. Phys. 107, 5496–5501 (1997)

  114. The effect of correlation on molecular magnetizabilities and rotational g tensors,
    K. Ruud, T. Helgaker, and P. Jørgensen,
    J. Chem. Phys. 107, 10599–10606 (1997)

    1998

  115. The Cotton–Mouton effect of liquid water. Part II: The semi-continuum model,
    K. Ruud, H. Ågren, P. Dahle, T. Helgaker, A. Rizzo, S. Coriani, H. Koch, K. O. Sylvester-Hvid, and K. V. Mikkelsen,
    J. Chem. Phys. 108, 599–603 (1998)

  116. Solvent effects on nuclear shieldings and spin–spin couplings of hydrogen selenide,
    P.-O. Åstrand, K. V. Mikkelsen, P. Jørgensen, K. Ruud, and T. Helgaker,
    J. Chem. Phys. 108, 2528–2537 (1998)

  117. Integral-direct coupled cluster calculations of frequency-dependent polarizabilities, transition probabilities and excited-state properties,
    O. Christiansen, A. Halkier, H. Koch, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 108, 2801–2816 (1998)

  118. The molecular Zeeman effect of nonbornadiene, its g-values, magnetizability anisotropies, and molecular quadrupole moment; a high-resolution microwave Fourier-transform study combined with quantum chemical calculations,
    K. Voges, D. H. Sutter, K. Ruud, and T. Helgaker,
    Z. Naturforsch. 53a, 67–76 (1998)

  119. The Hartree–Fock limit magnetizability of C60,
    K. Ruud, H. Ågren, T. Helgaker, P. Dahle, H. Koch, and P. R. Taylor,
    Chem. Phys. Lett. 285, 205–209 (1998)

  120. Spin–orbit and correlation effects in platinum hydride (PtH),
    M. Sjøvoll, H. Fagerli, O. Gropen, J. Almlöf, J. Olsen, and T. U. Helgaker,
    Int. J. Quantum Chem. 68, 53–64 (1998)

  121. Basis-set convergence in correlated calculations on Ne, N2, and H2O,
    A. Halkier, T. Helgaker, P. Jørgensen, W. Klopper, H. Koch, J. Olsen, and A. K. Wilson,
    Chem. Phys. Lett. 286, 243–252 (1998)

  122. Generalized integral-screening for efficient calculations of nonlinear optical properties of large molecules,
    K. Ruud, D. Jonsson, P. Norman, H. Ågren, T. Saue, H. J. Aa. Jensen, P. Dahle, and T. Helgaker
    J. Chem. Phys. 108, 7973–7979 (1998)

  123. Basis-set dependence of nuclear spin–spin coupling constants,
    T. Helgaker, M. Jaszuński, K. Ruud, and A. Górska,
    Theor. Chem. Acc. 99, 175–182 (1998)

  124. Extrapolation to the limit of a complete basis set for electronic structure calculations on the N2 molecule,
    W. Klopper and T. Helgaker,
    Theor. Chem. Acc. 99, 265–271 (1998)

  125. Full CI calculations of magnetic properties of the H2 molecule in the B1Σu+ state,
    T. Helgaker, M. Jaszuński, and K. Ruud,
    Pol. J. Chem. 72, 1405–1410 (1998)

  126. Electric and magnetic properties of fullerenes,
    D. Jonsson, P. Norman, K. Ruud, H. Ågren, and T. Helgaker,
    J. Chem. Phys. 109, 572–577 (1998)

  127. Electric field gradient, generalized Sternheimer shieldings and electric field gradient polarizabilities by multiconfigurational SCF response,
    A. Rizzo, K. Ruud, T. Helgaker, and M. Jaszuński,
    J. Chem. Phys. 109, 2264–2274 (1998)

  128. Rovibrational effects, temperature dependence, and isotope effects on the nuclear shielding tensors of water: A new 17O absolute shielding scale,
    J. Vaara, J. Lounila, K. Ruud, and T. Helgaker
    J. Chem. Phys. 109, 8388–8397 (1998)

  129. Atomic charges of the water molecule and the water dimer,
    P.-O. Åstrand, K. Ruud, K. V. Mikkelsen, and T. Helgaker,
    J. Phys. Chem. A 102, 7686–7691 (1998)

  130. Vibrationally averaged magnetizabilities and rotational g tensors of the water molecule,
    K. Ruud, J. Vaara, J. Lounila, and T. Helgaker,
    Chem. Phys. Lett. 297, 467–474 (1998)

  131. Gradient Theory,
    T. Helgaker,
    in The Encyclopedia of Computational Chemistry,
    P. v. R. Schleyer, N. L. Allinger, T. Clark, J. Gasteiger, P. A. Kollman, H. F. Schaefer III, and P. R. Schreiner, eds. (Wiley, Chichester, 1998), pp. 1157–1169

    1999

  132. Ab initio methods for the calculation of NMR shielding and indirect spin–spin coupling constants,
    T. Helgaker, M. Jaszuński, and K. Ruud,
    Chem. Rev. 99, 293–352 (1999)

  133. The calculation of molecular geometrical properties in the Hellmann–Feynman approximation,
    V. Bakken, T. Helgaker, W. Klopper, and K. Ruud,
    Mol. Phys. 96, 653–671 (1999)

  134. Basis-set convergence of the energy in molecular Hartree–Fock calculations,
    A. Halkier, T. Helgaker, P. Jørgensen, W. Klopper, and J. Olsen,
    Chem. Phys. Lett. 302, 437–446 (1999)

  135. Molecular polarizabilities and magnetizabilities,
    P. Dahle, K. Ruud, T. Helgaker, and P. R. Taylor,
    in Pauling’s Legacy: Modern Modelling of the Chemical Bond,
    Z. B. Maksic and W. J. Orville-Thomas, eds., (Elsevier Science, Amsterdam, 1999), pp. 147–188

  136. Rovibrationally averaged magnetizability, rotational g factor, and indirect spin–spin coupling of the hydrogen fluoride molecule,
    P.-O. Åstrand, K. Ruud, K. V. Mikkelsen, and T. Helgaker,
    J. Chem. Phys. 110, 9463–9468 (1999)

  137. Solvent effects on the NMR parameters of H2S and HCN
    K. V. Mikkelsen, K. Ruud, and T. Helgaker,
    J. Comput. Chem. 20, 1281–1291 (1999)

  138. Comment on “Geometry optimization with an infinite basis set” [J. Phys. Chem. A 103 (1999) 651] and “Basis-set extrapolation” [Chem. Phys. Lett. 294 (1998) 45],
    A. Halkier, T. Helgaker, W. Klopper, P. Jørgensen, and A. G. Császár,
    Chem. Phys. Lett. 310, 385–389 (1999)

  139. Basis-set convergence of the molecular dipole moment,
    A. Halkier, W. Klopper, T. Helgaker, and P. Jørgensen,
    J. Chem. Phys. 111, 4424–4430 (1999)

  140. Basis set convergence of the interaction energy of hydrogen-bonded complexes,
    A. Halkier, W. Klopper, T. Helgaker, P. Jørgensen, and P. R. Taylor,
    J. Chem. Phys. 111, 9157–9167 (1999)

  141. Grunnlaget for homøopati som behandlingsmetode,
    T. Greibrokk, T. Helgaker, and E. Uggerud,
    Tidsskr. Nor. Lægeforen. 119, 849–851 (1999)

  142. Highly accurate calculations of molecular electronic structure,
    W. Klopper, K. L. Bak, P. Jørgensen, J. Olsen, and T. Helgaker,
    J. Phys. B: At. Mol. Opt. Phys. 32, R103–R130 (1999)

    2000

  143. Coupled-cluster singles, doubles and triples (CCSDT) calculations of atomization energies,
    K. L. Bak, P. Jørgensen, J. Olsen, T. Helgaker, and J. Gauss,
    Chem. Phys. Lett. 317, 116–122 (2000)

  144. Basis-set convergence of the two-electron Darwin term,
    A. Halkier, T. Helgaker, W. Klopper, and J. Olsen,
    Chem. Phys. Lett. 319, 287–295 (2000)

  145. Perspective on “Neue Berechnung der Energie des Heliums im Grundzustande, sowie des tiefsten Terms von Ortho-Helium” [Hylleraas EA (1929) Z Phys 54: 347–366],
    T. Helgaker and W. Klopper,
    Theor. Chem. Acc. 103, 180–181 (2000)

  146. Accuracy of atomization energies and reaction enthalpies in standard and extrapolated electronic wave function/basis set calculations,
    K. L. Bak, P. Jørgensen, J. Olsen, T. Helgaker, and W. Klopper,
    J. Chem. Phys. 112, 9229–9242 (2000)

  147. Divergence in Møller–Plesset theory: A simple explanation based on a two-state model,
    J. Olsen, P. Jørgensen, T. Helgaker, and O. Christiansen,
    J. Chem. Phys. 112, 9736–9748 (2000)

  148. Accurate molecular geometries of the protonated water dimer,
    A. A. Auer, T. Helgaker, and W. Klopper,
    Phys. Chem. Chem. Phys. 2, 2235–2238 (2000)

  149. The accuracy of molecular dipole moments in standard electronic structure calculations,
    K. L. Bak, J. Gauss, T. Helgaker, P. Jørgensen, and J. Olsen,
    Chem. Phys. Lett. 319, 563–568 (2000)

  150. Molecular Electronic-Structure Theory,
    T. Helgaker, P. Jørgensen, and J. Olsen,
    Wiley, Chichester, 2000.

  151. Should gaseous BF3 and SiF4 be described as ionic compounds?,
    A. Haaland, T. U. Helgaker, K. Ruud, and D. J. Shorokhov,
    J. Chem. Ed. 77, 1076–1080 (2000)

  152. Nuclear shielding constants by density functional theory with gauge including atomic orbitals,
    T. Helgaker, P. J. Wilson, R. D. Amos, and N. C. Handy,
    J. Chem. Phys. 113, 2983–2989 (2000).

  153. Direct optimization of the AO density matrix in Hartree–Fock and Kohn–Sham theories,
    T. Helgaker, H. Larsen, J. Olsen, and P. Jørgensen,
    Chem. Phys. Lett. 327, 397–403 (2000)

  154. Gauge-origin independent magneto-optical activity within coupled cluster response theory,
    S. Coriani, C. Hättig, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 113, 3561–3572 (2000)

  155. Hartree–Fock and Kohn–Sham atomic-orbital based time-dependent response theory,
    H. Larsen, P. Jørgensen, J. Olsen, and T. Helgaker
    J. Chem. Phys. 113, 8908–8917 (2000)

  156. Analytical calculation of nuclear magnetic resonance indirect spin–spin coupling constants at the generalized gradient approximation and hybrid levels of density-functional theory
    T. Helgaker, M. Watson, and N. C. Handy,
    J. Chem. Phys. 113, 9402–9409 (2000)

    2001

  157. Highly accurate ab initio computation of thermochemical data,
    T. Helgaker, W. Klopper, K. L. Bak, A. Halkier, P. Jørgensen, and J. Olsen,
    in Understanding Chemical Reactivity, Vol. 22: Quantum-Mechanical Prediction of Thermochemical Data,
    J. Cioslowski, ed. (Kluwer, Dordrecht, 2001), pp. 1–30.

  158. The accurate determination of molecular equilibrium structures,
    K. L. Bak, J. Gauss, P. Jørgensen, J. Olsen, T. Helgaker, and J. F. Stanton,
    J. Chem. Phys. 114, 6548–6556 (2001)

  159. Chemical accuracy from ‘Coulomb hole’ extrapolated molecular quantum-mechanical calculations,
    K. L. Bak, A. Halkier, P. Jørgensen, J. Olsen, T. Helgaker, and W. Klopper,
    J. Mol. Struct. 567–568, 375–384 (2001)

  160. Efficient evaluation of one-center three-electron Gaussian integrals,
    P. Wind, T. Helgaker, and W. Klopper,
    Theor. Chem. Acc. 106, 280–286 (2001)

  161. Direct perturbation theory of magnetic properties and relativistic corrections for the point nuclear and Gaussian nuclear models,
    A. C. Hennum, W. Klopper, and T. Helgaker,
    J. Chem. Phys. 115, 7356–7363 (2001)

  162. Direct optimization of the atomic-orbital density matrix using the conjugate-gradient method with a multilevel preconditioner,
    H. Larsen, J. Olsen, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 115, 9685–9697 (2001)

  163. Geometrical derivatives and magnetic properties in atomic-orbital density-based Hartree–Fock theory,
    H. Larsen, T. Helgaker, J. Olsen, and P. Jørgensen,
    J. Chem. Phys. 115, 10344–10352 (2001)

    2002

  164. Basis-set completeness profiles in two dimensions,
    A. A. Auer, T. Helgaker, and W. Klopper,
    J. Comput. Chem. 23, 1–6 (2002)

  165. Second-order Møller–Plesset perturbation theory with terms linear in the interelectronic coordinates and exact evaluation of three-electron integrals,
    P. Wind, W. Klopper, and T. Helgaker,
    Theor. Chem. Acc. 107, 173–179 (2002)

  166. Optical rotation studied by density-functional and coupled-cluster methods,
    K. Ruud and T. Helgaker,
    Chem. Phys. Lett. 352, 533–539 (2002)

  167. Four-component relativistic Kohn–Sham theory,
    T. Saue and T. Helgaker
    J. Comput. Chem. 23, 814–823 (2002)

  168. Molecular equilibrium structures from experimental rotational constants and calculated vibration–rotation interaction constants,
    F. Pawłowski, P. Jørgensen, J. Olsen, F. Hegelund, T. Helgaker, J. Gauss, K. L. Bak, and J. F. Stanton,
    J. Chem. Phys. 116, 6482–6496 (2002)

  169. Parity-violating interaction in H2O2 calculated from density-functional theory,
    A. C. Hennum, T. Helgaker, and W. Klopper,
    Chem. Phys. Lett. 354, 274–282 (2002)

  170. Vibronic transitions from coupled-cluster response theory: Theory and application to HSiF and H2O,
    O. Christiansen, T. A. Ruden, K. Ruud, and T. Helgaker,
    J. Chem. Phys. 116, 8334–8342 (2002)

  171. Gauge-origin independent density-functional theory calculations of vibrational Raman optical activity,
    K. Ruud, T. Helgaker, and P. Bouř,
    J. Phys. Chem. A. 106, 7448–7455 (2002)

  172. Spin–spin coupling tensors by density-functional linear response theory,
    P. Lantto, J. Vaara, and T. Helgaker,
    J. Chem. Phys. 117, 5998–6009 (2002)

  173. Et virtuelt laboratorium: Kjemi på datamaskinen,
    T. Helgaker,
    Apollon Nr. 3, 2002, pp. 27–29

  174. Computation of two-electron Gaussian integrals for wave functions including the correlation factor r12exp(–γr212),
    C. C. M. Samson, W. Klopper, and T. Helgaker,
    Comp. Phys. Comm. 149, 1–10 (2002)

  175. The efficient optimization of molecular geometries using redundant internal coordinates,
    V. Bakken and T. Helgaker,
    J. Chem. Phys. 117, 9160–9174 (2002)

  176. Density-functional theory of linear and nonlinear time-dependent molecular properties,
    P. Sałek, O. Vahtras, T. Helgaker, and H. Ågren,
    J. Chem. Phys. 117, 9630–9645 (2002)

    2003

  177. Accuracy of spectroscopic constants of diatomic molecules from ab initio calculations,
    F. Pawłowski, A. Halkier, P. Jørgensen, K. L. Bak, T. Helgaker, and W. Klopper,
    J. Chem. Phys. 118, 2539–2549 (2003).

  178. A Lagrangian, integral-density direct formulation and implementation of the analytic CCSD and CCSD(T) gradients,
    K. Hald, A. Halkier, P. Jørgensen, S. Coriani, C. Hättig, and T. Helgaker,
    J. Chem. Phys. 118, 2985–2998 (2003)
    Publisher’s Note: “A Lagrangian, integral-density direct formulation and implementation of the analytic CCSD and CCSD(T) gradients” [J. Chem. Phys. 118, 2985 (2003)],
    K. Hald, A. Halkier, P. Jørgensen, S. Coriani, C. Hättig, and T. Helgaker,
    J. Chem. Phys. 118, 11335–11335 (2003)

  179. The spin–spin coupling constants in ethane, methanol and methylamine: a comparison of DFT, MCSCF and CCSD results,
    M. Pecul and T. Helgaker,
    Int. J. Mol. Sci. 4, 143–157 (2003)

  180. Coupled-cluster connected-quadruples corrections to atomization energies,
    T. A. Ruden, T. Helgaker, P. Jørgensen, and J. Olsen,
    Chem. Phys. Lett. 371, 62–67 (2003)

  181. Sternheimer shieldings and EFG polarizabilities: a density-functional theory study,
    A. Rizzo, K. Ruud, T. Helgaker, P. Sałek, H. Ågren, and O. Vahtras,
    Chem. Phys. Lett. 372, 377–385 (2003)

  182. Calculations of hydrogen-bond-transmitted indirect nuclear spin–spin couplings: a comparison of density-functional and ab initio methods,
    M. Pecul, J. Sadlej, and T. Helgaker,
    Chem. Phys. Lett. 372, 476–484 (2003)

  183. Vibrational corrections to indirect nuclear spin–spin coupling constants calculated by density-functional theory,
    T. A. Ruden, O. B Lutnæs, T. Helgaker, and K. Ruud,
    J. Chem. Phys. 118, 9572–9581 (2003)

  184. Density-functional theory calculation of the nuclear magnetic resonance indirect nuclear spin–spin coupling constants in C60,
    M. Jaszuński, K. Ruud, and T. Helgaker,
    Mol. Phys. 101, 1997–2002 (2003)

  185. Wave-function based quantum chemistry,
    T. Helgaker, P. Jørgensen, J. Olsen, and W. Klopper,
    in Computational Medicinal Chemistry for Drug Discovery,
    P. Bultinck, H. De Winter, W. Langenaeker, and J. Tollenaere eds., (Marcel Dekker, 2003), pp. 57–88

  186. Automated calculation of fundamental frequencies: Application to AlH3 using the coupled-cluster singles-and-doubles with perturbative triples method,
    T. A. Ruden, P. R. Taylor, and T. Helgaker,
    J. Chem. Phys. 119, 1951–1960 (2003)

  187. Calculations of two-photon absorption cross sections by means of density-functional theory,
    P. Sałek, O. Vahtras, J. Guo, Y. Luo, T. Helgaker, and H. Ågren,
    Chem. Phys. Lett. 374, 446–452 (2003)

  188. Characterization of dihydrogen-bonded D–H···H–A complexes on the basis of infrared and magnetic resonance spectroscopic parameters,
    H. Cybulski, M. Pecul, J. Sadlej, and T. Helgaker,
    J. Chem. Phys. 119, 5094–5104 (2003)

  189. Density-functional theory of nonlinear triplet response properties with applications to phosphorescence,
    I. Tunell, Z. Rinkevicius, O. Vahtras, P. Sałek, T. Helgaker, and H. Ågren,
    J. Chem. Phys. 119, 11024–11034 (2003)

    2004

  190. The NMR indirect nuclear spin–spin coupling constants for some small rigid hydrocarbons: molecular equilibrium values and vibrational corrections,
    T. A. Ruden, T. Helgaker, and M. Jaszuński,
    Chem. Phys. 296, 53–62 (2004)

  191. Density functional theory calculation of electronic circular dichroism using London orbitals,
    M. Pecul, K. Ruud, and T. Helgaker,
    Chem. Phys. Lett. 388, 110–119 (2004)

  192. Potential energy and spin–spin coupling constants surface of glycolaldehyde,
    T. Ratajczyk, M. Pecul, J. Sadlej, and T. Helgaker,
    J. Phys. Chem. A 108, 2758–2769 (2004)

  193. Density-functional theory calculations of optical rotatory dispersion in the nonresonant and resonant frequency regions,
    P. Norman, K. Ruud, and T. Helgaker,
    J. Chem. Phys. 120, 5027–5035 (2004)

  194. Density-functional generalized-gradient and hybrid calculations of electromagnetic properties using Slater basis sets,
    M. A. Watson, N. C. Handy, A. J. Cohen, and T. Helgaker,
    J. Chem. Phys. 120, 7252–7261 (2004)

  195. Calculation of electric dipole hypershieldings at the nuclei in the Hellmann–Feynman approximation,
    A. Soncini, P. Lazzeretti, V. Bakken, and T. Helgaker,
    J. Chem. Phys. 120, 3142–3151 (2004)

  196. Spin–spin coupling constants with HF and DFT methods,
    T. Helgaker and M. Pecul,
    In Calculation of NMR and EPR Parameters: Theory and Applications,
    M. Kaupp, M. Bühl, and V. G. Malkin, eds. (Wiley-VCH, Weinheim 2004), pp. 101–121

  197. Conformational effects on the optical rotation of alanine and proline,
    M. Pecul, K. Ruud, A. Rizzo, and T. Helgaker,
    J. Phys. Chem. A 108, 4269–4276 (2004)

  198. The trust-region self-consistent field method: Towards a black-box optimization in Hartree–Fock and Kohn–Sham theories,
    L. Thøgersen, J. Olsen, D. Yeager, P. Jørgensen, P. Sałek, and T. Helgaker,
    J. Chem. Phys. 121, 16–27 (2004)

  199. GIAO shielding constants and indirect spin–spin coupling constants: performance of density functional methods,
    T. W. Keal, D. J. Tozer, and T. Helgaker,
    Chem. Phys. Lett. 391, 374 –379 (2004)

  200. Linear-scaling formation of Kohn–Sham Hamiltonian: Application to the calculation of excitation energies and polarizabilities of large molecular systems,
    M. A. Watson, P. Sałek, P. Macak, and T. Helgaker,
    J. Chem. Phys. 121, 2915–2931 (2004)

  201. Polarization consistent basis sets. V. The elements Si–Cl,
    F. Jensen and T. Helgaker,
    J. Chem. Phys. 121, 3463–3470 (2004)

  202. The expansion of hydrogen states in Gaussian orbitals,
    V. Bakken and T. Helgaker,
    Theor. Chem. Acc. 112, 124–134 (2004)

  203. The calculation of indirect nuclear spin–spin coupling constants in large molecules,
    M. A. Watson, P. Sałek, P. Macak, M. Jaszuński, and T. Helgaker,
    Chem. Eur. J. 10, 4627–4639 (2004)

  204. A priori calculation of molecular properties to chemical accuracy,
    T. Helgaker, T. A. Ruden, P. Jørgensen, J. Olsen, and W. Klopper,
    J. Phys. Org. Chem. 17, 913–933 (2004)

  205. The performance of hybrid density functional theory for the calculation of indirect nuclear spin–spin coupling constants in substituted hydrocarbons,
    O. B. Lutnæs T. A. Ruden, and T. Helgaker,
    Magn. Reson. Chem. 42, S117–S127 (2004)

  206. Coupled-cluster connected quadruples and quintuples corrections to the harmonic vibrational frequencies and equilibrium bond distances of HF, N2, F2, and CO,
    T. A. Ruden, T. Helgaker, P. Jørgensen, and J. Olsen,
    J. Chem. Phys. 121, 5874–5884 (2004)

  207. A closed-shell coupled-cluster treatment of the Breit–Pauli first-order relativistic energy correction,
    S. Coriani, T. Helgaker, P. Jørgensen, and W. Klopper,
    J. Chem. Phys. 121, 6591–6598 (2004)

  208. First-order relativistic corrections to response properties: the hyperpolarizability of the Ne atom,
    W. Klopper, S. Coriani, T. Helgaker, and P. Jørgensen,
    J. Phys. B: At. Mol. Opt. Phys. 37, 3753–3763 (2004)

  209. Models of fragmentations induced by electron attachment to protonated peptides,
    V. Bakken, T. Helgaker, and E. Uggerud,
    Eur. J. Mass Spectrom. 10, 625–638 (2004)

  210. A comparison of polarization and bond functions for density functional calculations,
    J. Bruun, T. Helgaker, and F. Jensen,
    Mol. Phys. 102, 2559-2562 (2004)

    2005

  211. A comparison of density-functional-theory and coupled-cluster frequency-dependent polarizabilities and hyperpolarizabilities,
    P. Sałek, T. Helgaker, O. Vahtras, H. Ågren, D. Jonsson, and J. Gauss,
    Mol. Phys. 103, 439–450 (2005)

  212. Linear response at the 4-component relativistic density-functional level: application to the frequency-dependent dipole polarizability of Hg, AuH and PtH2,
    P. Sałek, T. Helgaker, and T. Saue,
    Chem. Phys. 311, 187–201 (2005)

  213. Atmospheric chemistry of CHF2CHO: Study of the IR and UV-vis absorption cross sections, photolysis, and OH-, Cl-, and NO3-initiated oxidation,
    S. R. Sellevåg, Y. Stenstrøm, T. Helgaker, and C. J. Nielsen,
    J. Phys. Chem. A 109, 3652–3662 (2005)

  214. Theoretical studies of nuclear magnetic resonance parameters for the proton-exchange pathways in porphyrin and porphycene,
    H. Cybulski, M. Pecul, T. Helgaker, and M. Jaszuński,
    J. Phys. Chem. A 109, 4162–4171 (2005)

  215. Density-functional theory study of electric and magnetic properties of hexafluorobenzene in the vapor phase,
    A. Rizzo, C. Cappelli, B. Jansík, D. Jonsson, P. Sałek, S. Coriani, D. J. D. Wilson, T. Helgaker, and H. Ågren,
    J. Chem. Phys. 122, 234314 (2005),
    Erratum, J. Chem. Phys. 129, 039901 (2008)

  216. The trust-region self-consistent field method in Kohn–Sham density-functional theory,
    L. Thøgersen, J. Olsen, A. Köhn, P. Jørgensen, P. Sałek, and T. Helgaker,
    J. Chem. Phys. 123, 074103 (2005)

  217. The rotational g tensor as a benchmark for density-functional theory calculations of molecular magnetic properties,
    D. J. D. Wilson, C. E. Mohn, and T. Helgaker,
    J. Chem. Theory Comput. 1, 877–888 (2005)

  218. A computational study of some electric and magnetic properties of gaseous BF3 and BCl3,
    A. Rizzo, C. Cappelli, J. M. Junquera-Hernández, A. M. J. Sánchez de Merás, J. Sánchez-Marín, D. J. D. Wilson, and T. Helgaker,
    J. Chem. Phys. 123, 114307 (2005),
    Erratum, J. Chem. Phys. 129, 039901 (2008)

  219. The accuracy of ab initio molecular geometries for systems containing second-row atoms,
    S. Coriani, D. Marchesan, J. Gauss, C. Hättig, T. Helgaker, and P. Jørgensen,
    J. Chem. Phys. 123, 184107 (2005)

  220. Calculations of two-photon charge-transfer excitations using Coulomb-attenuated density-functional theory,
    E. Rudberg, P. Sałek, T. Helgaker, and H. Ågren,
    J. Chem. Phys. 123, 184108 (2005)

  221. The rotational g tensor as a benchmark for ab initio molecular property calculations,
    C. E. Mohn, D. J. D. Wilson, O. B. Lutnæs, T. Helgaker, and K. Ruud,
    Adv. In Quantum Chem. 50, 77–90 (2005)

  222. Quadratic response functions in a second-order polarization propagator framework,
    J. Olsen, P. Jørgensen, T. Helgaker, and J. Oddershede,
    J. Phys. Chem. A 109, 11618–11628 (2005)

    2006

  223. The equilibrium structure of ferrocene,
    S. Coriani, A. Haaland, T. Helgaker, and P. Jørgensen,
    ChemPhysChem 7, 245–249 (2006)

  224. Assessment of a Coulomb-attenuated exchange–correlation energy functional,
    M. J. G. Peach, T. Helgaker, P. Sałek, T. W. Keal, O. B. Lutnæs, D. J. Tozer, and N. C. Handy,
    Phys. Chem. Chem. Phys. 8, 558–562 (2006)

  225. Benchmarking two-photon absorption with CC3 quadratic response theory, and comparison with density-functional response theory,
    M. J. Paterson, O. Christiansen, F. Pawłowski, P. Jørgensen, C. Hättig, T. Helgaker, and P. Sałek,
    J. Chem. Phys. 124, 054322 (2006)

  226. The magnetizability, rotational g tensor and quadrupole moment of the boron trihalides,
    D. J. D. Wilson, T. Helgaker, and A. Rizzo,
    Mol. Phys. 104, 847–856 (2006)

  227. Rotational g tensors calculated using hybrid exchange–correlation functionals with the optimized effective potential approach,
    O. B. Lutnæs, A. M. Teale, T. Helgaker, and D. J. Tozer,
    J. Chem. Theory Comput. 2, 827–834 (2006)

  228. Choice of exchange–correlation functional for computing NMR indirect spin–spin coupling constants,
    T. W. Keal, T. Helgaker, P. Sałek, and D. J. Tozer,
    Chem. Phys. Lett. 425, 163–166 (2006)

  229. Density-functional-theory study of the electric-field-induced second harmonic generation (EFISHG) of push–pull phenylpolyenes in solution,
    L. Ferrighi, L. Frediani, C. Cappelli, P. Sałek, H. Ågren, T. Helgaker, and K. Ruud,
    Chem. Phys. Lett. 425, 267–272 (2006)

  230. A second-quantization framework for the unified treatment of relativistic and nonrelativistic molecular perturbations by response theory,
    T. Helgaker, A. C. Hennum, and W. Klopper,
    J. Chem. Phys. 125, 024102 (2006)

  231. Towards black-box linear scaling optimization in Hartree–Fock and Kohn–Sham theories,
    S. Høst, J. Olsen, B. Jansík, P. Jørgensen, S. Reine, T. Helgaker, P. Sałek, and S. Coriani,
    in Lecture Series on Computer and Computational Sciences, Vol. 6: Trends and Perspectives in Modern Computational Science,
    G. Maroulis and T. E. Simos, ed. (Brill Academic Publishers, Leiden, 2006), pp. 177–189

    2007

  232. Density-functional and coupled-cluster singles-and-doubles calculations of the nuclear shielding and indirect nuclear spin–spin coupling constants of o-benzyne,
    T. Helgaker, O. B. Lutnæs, and M. Jaszuński,
    J. Chem. Theory Comput. 3, 86–94 (2007)

  233. Electron correlation: the many-body problem at the heart of chemistry,
    D. P. Tew, W. Klopper, and T. Helgaker,
    J. Comput. Chem. 28, 1307–1320 (2007)

  234. Linear-scaling implementation of molecular electronic self-consistent field theory,
    P. Sałek, S. Høst, L. Thøgersen, P. Jørgensen, P. Manninen, J. Olsen, B. Jansík, S. Reine, F. Pawłowski, E. Tellgren, T. Helgaker, and S. Coriani
    J. Chem. Phys. 126, 114110 (2007)

  235. Linear-scaling symmetric square-root decomposition of the overlap matrix,
    B. Jansík, S. Høst, P. Jørgensen, J. Olsen, and T. Helgaker,
    J. Chem. Phys. 126, 124104 (2007)

  236. Linear-scaling implementation of molecular response theory in self-consistent field electronic-structure theory,
    S. Coriani, S. Høst, B. Jansík, L. Thøgersen, J. Olsen, P. Jørgensen, S. Reine, F. Pawłowski, T. Helgaker, and P. Sałek,
    J. Chem. Phys. 126, 154108 (2007)

  237. Accurate quantum-chemical calculations using Gaussian-type geminal and Gaussian-type orbital basis sets: applications to atoms and diatomics,
    P. Dahle, T. Helgaker, D. Jonsson, and P. R. Taylor,
    Phys. Chem. Chem. Phys. 9, 3112–3126 (2007)

  238. A unified scheme for the calculation of differentiated and undifferentiated molecular integrals over solid-harmonic Gaussians,
    S. Reine, E. Tellgren, and T. Helgaker,
    Phys. Chem. Chem. Phys. 9, 4771–4779 (2007)

  239. Electronic circular dichroism of disulphide bridge: Ab initio quantum-chemical calculations,
    W. Skomorowski, M. Pecul, P. Sałek, and T. Helgaker,
    J. Chem. Phys. 127, 085102 (2007)

  240. Structural and electronic properties of polyacetylene and polyyne from hybrid and Coulomb-attenuated density functionals,
    M. J. G. Peach, E. I. Tellgren, P. Sałek, T. Helgaker, and D. J. Tozer,
    J. Phys. Chem. A 111, 11930–11935 (2007)

  241. Explicit electron correlation by a combined use of Gaussian-type orbitals and Gaussian-type geminals,
    P. Dahle, T. Helgaker, D. Jonsson, and P. R. Taylor,
    in Computation in Modern Science and Engineering, Proceedings of the International Conference on Computational Methods in Science and Engineering 2007,
    G. Maroulis and T. E. Simos, ed. (American Institute of Physics 2007), Vol. 2 Part A, pp. 187–190

    2008

  242. Static and frequency-dependent dipole–dipole polarizabilities of all closed-shell atoms up to radium: A four-component relativistic DFT study,
    R. Bast, A. Heßelmann, P. Sałek, T. Helgaker, and T. Saue,
    ChemPhysChem 9, 1–10 (2008)

  243. Excitation energies in density functional theory: An evaluation and a diagnostic test,
    M. J. G. Peach, P. Benfield, T. Helgaker, and D. J. Tozer,
    J. Chem. Phys. 128, 044118 (2008)
    [Supplementary Information: EPAPS Document No. E-JCPSA6-128-029805]

  244. Second-order Møller–Plesset calculations on the water molecule using Gaussian-type orbital and Gaussian-type geminal theory,
    P. Dahle, T. Helgaker, D. Jonsson, and P. R. Taylor,
    Phys. Chem. Chem. Phys. 10, 3377–3382 (2008)

  245. Erratum: “Density-functional and electron correlated study of five linear birefringences—Kerr, Cotton–Mouton, Buckingham, Jones and magnetoelectric—in gaseous benzene” [J. Chem. Phys. 121, 8814 (2004)]; “Density-functional study of electric and magnetic properties of hexafluorobenzene in the vapor phase” [J. Chem. Phys. 122, 234314 (2005)]; and “A computational study of some electric and magnetic properties of gaseous BF3 and BCl3” [J. Chem. Phys. 123, 114307 (2005)],
    A. Rizzo, C. Cappelli, B. Jansík, D. Jonsson, P. Sałek, S. Coriani, H. Ågren, D. J. D. Wilson, T. Helgaker, J. M. Junquera–Hernández, A. M. J. Sánchez de Merás, and J. Sánchez-Marín,
    J. Chem. Phys. 129, 039901 (2008)

  246. Hartree–Fock and Kohn–Sham time-dependent response theory in a second-quantization atomic-orbital formalism suitable for linear scaling,
    T. Kjærgaard, P. Jørgensen, J. Olsen, S. Coriani, and T. Helgaker,
    J. Chem. Phys. 129, 054106 (2008)

  247. Maps of current density using density-functional methods,
    A. Soncini, A. M. Teale, T. Helgaker, F. De Proft, and D. J. Tozer,
    J. Chem. Phys. 129, 074101 (2008)

  248. The quantum-chemical calculation of NMR indirect spin–spin coupling constants,
    T. Helgaker, M. Jaszuński, and M. Pecul,
    Prog. Nucl. Magn. Reson. Spectrosc. 53, 249–268 (2008)

  249. A ground-state-directed optimization scheme for the Kohn–Sham energy,
    S. Høst, B. Jansík, J. Olsen, P. Jørgensen, S. Reine, and T. Helgaker,
    Phys. Chem. Chem. Phys. 10, 5344–5348 (2008)

  250. Variational and robust density fitting of four-center two-electron integrals in local metrics,
    S. Reine, E. Tellgren, A. Krapp, T. Kjærgaard, T. Helgaker, B. Jansík, S. Høst, and P. Sałek,
    J. Chem. Phys. 129, 104101 (2008)

  251. The augmented Roothaan–Hall method for optimizing Hartree–Fock and Kohn–Sham density matrices,
    S. Høst, J. Olsen, B. Jansík, L. Thøgersen, P. Jørgensen, and T. Helgaker,
    J. Chem. Phys. 129, 124106 (2008)

  252. Nonperturbative ab initio calculations in strong magnetic fields using London orbitals,
    E. I. Tellgren, A. Soncini, and T. Helgaker,
    J. Chem. Phys. 129, 154114 (2008)

  253. Quantitative quantum chemistry,
    T. Helgaker, W. Klopper, and D. P. Tew,
    Mol. Phys. 106, 2107–2143 (2008)

  254. Density-functional calculations of the nuclear magnetic shielding and indirect nuclear spin–spin coupling constants of three isomers of C20,
    O. B. Lutnæs, T. Helgaker, and M. Jaszuński,
    Mol. Phys. 106, 2357–2365 (2008)

  255. Efficient elimination of response parameters in molecular property calculations for variational and nonvariational energies,
    K. Kristensen, P. Jørgensen, A. J. Thorvaldsen, and T. Helgaker,
    J. Chem. Phys. 129, 214103 (2008)

    2009

  256. The geminal basis in explicitly correlated wave functions,
    S. Höfener, D. P. Tew, W. Klopper, and T. Helgaker,
    Chem. Phys. 356, 25–30 (2009)

  257. The calculation of adiabatic-connection curves from full configuration-interaction densities: Two-electron systems,
    A. M. Teale, S. Coriani, and T. Helgaker,
    J. Chem. Phys. 130, 104111 (2009)

  258. Robust and reliable multilevel minimization of the Kohn–Sham energy,
    B. Jansík, S. Høst, M. P. Johansson, J. Olsen, P. Jørgensen, and T. Helgaker,
    J. Chem. Theory Comput. 5, 1027–1032 (2009)

  259. Non-perturbative magnetic phenomena in closed-shell paramagnetic molecules,
    E. I. Tellgren, T. Helgaker, and A. Soncini,
    Phys. Chem. Chem. Phys. 11, 5489–5498 (2009)

  260. A stepwise atomic, valence-molecular, and full-molecular optimisation of the Hartree–Fock/Kohn–Sham energy,
    B. Jansík, S. Høst, M. P. Johansson, J. Olsen, P. Jørgensen, and T. Helgaker,
    Phys. Chem. Chem. Phys. 11, 5805–5813 (2009)

  261. Benchmarking density-functional-theory calculations of rotational g tensors and magnetizabilities using accurate coupled-cluster calculations,
    O. B. Lutnæs, A. M. Teale, T. Helgaker, D. J. Tozer, K. Ruud, and J. Gauss,
    J. Chem. Phys. 131, 144104 (2009)
    [Supplementary Information: EPAPS Document No. E-JCPSA6-131-007939]

  262. Implementation of the incremental scheme for one-electron first-order properties in coupled-cluster theory,
    J. Friedrich, S. Coriani, T. Helgaker, and M. Dolg,
    J. Chem. Phys. 131, 154102 (2009)
    [Supplementary Information: EPAPS Document No. E-JCPSA6-131-038939]

  263. Assessment of theoretical methods for the determination of the mechanochemical strength of covalent bonds,
    M. F. Iozzi, T. Helgaker, and E. Uggerud,
    Mol. Phys. 107, 2537–2546 (2009)

    2010

  264. Accurate calculation and modelling of the adiabatic connection in density functional theory,
    A. M. Teale, S. Coriani, and T. Helgaker,
    J. Chem. Phys. 132, 164115 (2010)

  265. An efficient density-functional-theory force evaluation for large molecular systems,
    S. Reine, A. Krapp, M. F. Iozzi, V. Bakken, T. Helgaker, F. Pawłowski, and P. Sałek,
    J. Chem. Phys. 133, 044102 (2010)

  266. Range-dependent adiabatic connections,
    A. M. Teale, S. Coriani, and T. Helgaker,
    J. Chem. Phys. 133, 164112 (2010)

  267. Spin–spin coupling constants and triplet instabilities in Kohn–Sham theory,
    O. B. Lutnæs, M. Jaszuński, and T. Helgaker,
    Mol. Phys. 108, 2579–2590 (2010)

  268. The scientific case for eInfrastructure in Norway,
    G. Gisler, E. Celledoni, T. U. Helgaker, T. Iversen, K. S. Jakobsen, C. Jones, A. Lipniacka, A. Lundervold, N. R. B. Olsen, and K. De Smedt,
    The Research Council of Norway, Oslo, 2010 (ISBN 978-82-12-02831-9)

    2011

  269. The ab initio calculation of molecular electric, magnetic and geometric properties,
    R. Bast, U. Ekström, B. Gao, T. Helgaker, K. Ruud, and A. J. Thorvaldsen,
    Phys. Chem. Chem. Phys. 13, 2627–2651 (2011)

  270. Influence of external force on properties and reactivity of disulfide bonds,
    M. F. Iozzi, T. Helgaker, and E. Uggerud,
    J. Phys. Chem. A 115, 2308–2315 (2011)

  271. Relativistic four-component calculations of Buckingham birefringence using London atomic orbitals,
    R. Bast, K. Ruud, A. Rizzo, and T. Helgaker,
    Theor. Chem. Acc. 129, 685–699 (2011)

  272. Spin flipping in ring-coupled-cluster-doubles theory,
    W. Klopper, A. M. Teale, S. Coriani, T. B. Pedersen, and T. Helgaker,
    Chem. Phys. Lett. 510, 147–153 (2011)

  273. Molecules in strong magnetic fields,
    T. Helgaker, K. K. Lange, and E. I. Tellgren
    Meta, No. 3, 2011, pp. 16–18

  274. Chemistry and materials,
    T. Helgaker,
    Kjemi, No. 5, 2011, pp. 10–11,
    Reprinted from: The scientific case for eInfrastructure in Norway, The Research Council of Norway, Oslo, 2010

  275. Dispersion interactions in density-functional theory: an adiabatic-connection analysis,
    M. D. Strømsheim, N. Kumar, S. Coriani, E. Sagvolden, A. M. Teale, and T. Helgaker,
    J. Chem. Phys. 135, 194109 (2011)

    2012

  276. A theoretical study on hydrogen transport mechanism in SrTiO3 perovskite,
    T. Onishi and T. Helgaker,
    Int. J. Quantum Chem. 112, 201–207 (2012)

  277. Recent advances in wave function-based methods of molecular-property calculations,
    T. Helgaker, S. Coriani, P. Jørgensen, K. Kristensen, J. Olsen, and K. Ruud,
    Chem. Rev. 112, 543–631 (2012)

  278. Multi-electron integrals,
    S. Reine, T. Helgaker, and R. Lindh,
    WIREs Comput. Mol. Sci. 2, 290–303 (2012)

  279. Calculation of the two-electron Darwin term using explicitly correlated wave functions,
    N. Middendorf, S. Höfener, W. Klopper, and T. Helgaker,
    Chem. Phys. 401, 146–151 (2012)

  280. Analytical GIAO and hybrid-basis integral derivatives: application to geometry optimization of molecules in strong magnetic fields,
    E. I. Tellgren, S. S. Reine, and T. Helgaker,
    Phys. Chem. Chem. Phys. 14, 9492–9499 (2012)

  281. A paramagnetic bonding mechanism for diatomics in strong magnetic fields,
    K. K. Lange, E. I. Tellgren, M. R. Hoffmann, and T. Helgaker,
    Science 337, 327–331 (2012)

  282. Forword,
    J. Gauss, T. Helgaker, and J. Stanton,
    Mol. Phys. 110, 2313–2313 (2012)

  283. The NMR indirect nuclear spin–spin coupling constant of the HD molecule,
    T. Helgaker, M. Jaszuński, P. Garbacz, and K. Jackowski,
    Mol. Phys. 110, 2611–2617 (2012)

  284. Range-dependent adiabatic connections,
    A. M. Teale, S. Coriani, and T. Helgaker,
    AIP Conf. Proc. 1504, 92–99 (2012)

  285. Choice of basic variables in current-density-functional theory,
    E. I. Tellgren, S. Kvaal, E. Sagvolden, U. Ekström, A. M. Teale, and T. Helgaker,
    Phys. Rev. A 86, 062506 (2012)

    2013

  286. Benchmarking density-functional theory calculations of NMR shielding constants and spin–rotation constants using accurate coupled-cluster calculations,
    A. M. Teale, O. B. Lutnæs, T. Helgaker, D. J. Tozer, and J. Gauss,
    J. Chem. Phys. 138, 024111 (2013)

  287. A theoretical study on the hydrogen transport mechanism in SrTiO3 perovskite. II. Scandium doping at titanium site,
    T. Onishi and T. Helgaker,
    Int. J. Quantum Chem. 113, 599–604 (2013)

  288. Insights into the dynamics of evaporation and proton migration in protonated water clusters from large-scale Born–Oppenheimer direct dynamics,
    V. V. Rybkin, A. O. Simakov, V. Bakken, S. Reine, T. Kjærgaard, T. Helgaker, and E. Uggerud,
    J. Comp. Chem. 34, 533–544 (2013)

  289. Attractive electron–electron interactions within robust local fitting approximations,
    P. Merlot, T. Kjærgaard, T. Helgaker, R. Lindh, F. Aquilante, S. Reine, and T. B. Pedersen,
    J. Comp. Chem. XX, XXX–XXX (2013)