Modifications are proposed to the Stillinger-Weber potential, a semiempirical interaction potential for silicon. The modifications are specifically intended to improve the description of the amorphous phase. The potential is adjusted to reproduce the location of the transverse optic (TO) and transverse acoustic (TA) peaks of the vibrational density of states. These modifications also lead to ex...

In this article the authors deal with the experimental and theoretical interpretation of the vibrational spectra of trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene) of diverse beneficial biological activity. Infrared and Raman spectra of the compound were recorded; density functional calculations were carried out resulting in the optimized geometry and several properties of the molecule. Ba...

The catalytic properties of gold nanoparticles are determined by their electronic and geometric structures. We revealed the geometries of several small neutral gold clusters in the gas phase by using vibrational spectroscopy between 47 and 220 wavenumbers. A two-dimensional structure for neutral Au7 and a pyramidal structure for neutral Au20 can be unambiguously assigned. The reduction of the s...

In addition to their ground state, diamond structure, Si, Ge and Sn can form crystalline solids called clathrates. As in the diamond structure, in the clathrates, the Group IV atoms are tetrahedrally coordinated and sp covalently bonded to their neighbors. However, the clathrates contain pentagonal atomic rings and have open-framework lattices containing 20-, 24and 28-atom ‘‘cages’’. There are ...

Electronic speckle pattern interferometry (ESPI) was used for the evaluation of mechanical properties of automobile tires. The tire on wheel disc was fixed on the holder and its vibration was generated by loudspeaker. Vibrational field of the whole tire was visualized by ESPI and recorded into PC. Natural frequencies of various vibrational modes were measured and results were compared with thos...

We performed a first principles total energy investigation on the structural, electronic, and vibrational properties of adamantane molecules, functionalized with amine and ethanamine groups. We computed the vibrational signatures of amantadine and rimantadine isomers with the functional groups bonded to different carbon sites. By comparing our results with recent infrared and Raman spectroscopi...

Carvedilol (CRV) is an important medicament for heart arrhythmia. The aim of this work was the interpretation of its vibrational spectra with consideration on the solvent effect. Infrared and Raman spectra were recorded in solid state as well in solution. The experimental spectra were evaluated using DFT quantum chemical calculations computing the optimized structure, atomic net charges, vibrat...

The anomalous thermodynamic properties of glasses remain incompletely understood, notably the anomalous peak in the heat capacity at low temperatures; it is believed to be due to an excess of low-frequency vibrational modes and a manifestation of the structural disorder in these systems. We study the thermodynamics and vibrational dynamics of colloidal glasses and (defected) crystals. The exper...

in this paper,the molecular geometry for three tautomers of uracil and four tautomers of cytosine has been analyzed. vibrational ir spectra of the tautomers were   investigated at hf and b3lyp level using the ab initio 6-31g* and lanl2dz basis sets from the program package gaussian 98 (a.7 public domain version). the physico-chemical and biochemical properties of uracil and cytosine are one of...

A first-principles spin-polarised local density functional cluster method is used to explore the structural and vibrational properties of several substitutional transition-metal impurities complexed with hydrogen.