Welcome to Density Functional Theory based database (DFTBD) web site

This database is intended to provide scientists (experimental as well as theoretical) with a central source of reliable inorganic data in the area of Raman and IR spectroscopy. Inorganic compounds included in this collection were selected to provide representative materials for identification and classification. At present there are 3,745 theoretical spectra (3130 experimental spectra; collected from literatures) in the database and they were simulated from very accurate and expensive calculations (optimized with respect to stress and strain; as much as possible cut-off energy, k-points, etc.) using different advanced DFT codes. This data base is updated on the daily basis, whenever the data passed our reliability test (different type of simulation) and are update immediately. The analytical applications of this database include identification of phases, quality control (impurities and secondary phases), materials selection and other applications such as process control. These applications in nearly all cases require some type of reference spectra to classify the materials. more ...

Density Functional Theory based electronic structure database: At present we have 25,065 compounds in the DFTBD-Electro database.

Density Functional Theory based mechanical properties database: At present we have 10,332 compounds in the DFTBD-Mecha database.

Density Functional Theory based thermodynamics database: At present we have 10,030 compounds in the DFTBD-Thermo database.

Density Functional Theory based optical properties database: At present we have 539 compounds in the DFTBD-Optic database.

Raman exp picture Raman spectra

Raman spectroscopy has become an important analytical and research tool. It can be used for applications as wide ranging as pharmaceuticals, forensic science, polymers, thin films, semiconductors, nano-phase materials, and even for the analysis of fullerene structures and carbon nano-materials. Raman spectroscopy is used to study the vibrational, rotational, and other low-frequency modes in a system. Raman spectroscopy is a light scattering technique, and can be thought of in its simplest form as a process where a photon of light interacts with a sample to produce scattered radiation of different wavelengths. This technique is extremely information rich, (useful for chemical identification, characterization of molecular structures, effects of bonding, environment and stress on a sample). From this method one can study the vibrational, rotational, and other low-frequency modes in a system. It is based on the Raman effect of inelastic scattering of monochromatic light. This interaction with vibrations results in the energy of incident photons being shifted up or down. The energy shift is defined by the vibrational frequency and the proportion of the inelastically scattered light is defined by the spatial derivatives of the macroscopic polarization. (read more ...) .

IR data Infrared (IR) spectra

Infrared spectroscopy exploits the fact that molecules absorb specific frequencies that are characteristic of their structure. These absorptions are resonant frequencies, i.e. the frequency of the absorbed radiation matches the frequency of the bond or group that vibrates. The energies are determined by the shape of the molecular potential energy surfaces, the masses of the atoms, and the associated vibronic coupling. Infrared (IR) spectroscopy is one of the most common spectroscopic techniques used by organic and inorganic chemists. Simply, it is the absorption measurement of different IR frequencies by a sample positioned in the path of an IR beam. The main goal of IR spectroscopic analysis is to determine the chemical functional groups in the sample. Different functional groups absorb characteristic frequencies of IR radiation. Using various sampling accessories, IR spectrometers can accept a wide range of sample types such as gases, liquids, and solids. Thus, IR spectroscopy is an important and popular tool for structural elucidation and compound identification. (more details ...)

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In addition to the Raman and IR spectra one can also find the following properties/data for the available compounds:

1) Raman and IR active frequencies and intensity.

2) Optical dielectric permittivity and molecular polarizability.

3) Born effective charges (also known as atomic polarizability tensors)

4) Single crystal elastic constants (Cij, etc.)

5) NMR related parameters (Iso, Aniso, Cq, etc.) more ...