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نتایج جستجو برای Vibrational properties

تعداد نتایج: 507634  
2003
Enrique J. Baran,

Bismutine, BiH3, is the least stable of the group15 trihydrides. F. Paneth first detected it in minute traces in 1918 using a radiochemical technique involving Bi2Mg3 [1]. The best preparation method seems to be the one proposed by Amberger in 1961, based on the disproportionation of CH3BiH2 at −45 ◦C[̃2]. This relatively complex synthesis has recently been successfully reproduced and allowed to...

2005
Enrique J. Baran,

Z. Naturforsch. 60a, 408 – 410 (2005); received March 2, 2005 On the basis of the most recently reported spectroscopic data on vibrational modes in TeCl4 and structural parameters of TeCl4, an estimation of its main force constants complemented with the calculation of mean amplitudes of vibration in a wide temperature range have been performed. Also thermodynamic functions for the ideal gaseous...

2015
Hari P. Lamichhane, Gary Hastings, Philip Crooke,

Density functional theory has been used to calculate harmonic normal mode vibrational frequencies for unlabeled and isotope-labeled ubisemiquinones in both the gas phase and in several solvents. It is shown that four methoxy group conformations are likely to be present in solution at room temperature. Boltzmann weighted infrared and Raman spectra for the four conformers were calculated, and com...

Gholarn Hossein Shafiee, Hadi Shafice, Jamshid Najafpour, Seyed Abdolreza Sadjadi,

It seems that the general applicability of the quantum theory of atoms in molecules (QTAIM) oncharacterizing the bonded interactions is still questionable even afier 30 years since its formulation. Fordemonstrating the generality of bonding schemes in QTA IM, ea( isomers were chosen as the modelsystems and the results from molecular charge density analysis and vibrational normal modes werecompa...

Journal: :Physical chemistry chemical physics : PCCP 2007
Ove Christiansen,

A number of recently developed theoretical methods for the calculation of vibrational energies and wave functions are reviewed. Methods for constructing the appropriate quantum mechanical Hamilton operator are briefly described before reviewing a particular branch of theoretical methods for solving the nuclear Schrödinger equation. The main focus is on wave function methods using the vibrationa...

2004
Enrique J. Baran,

Astatine (Z = 85) is the heaviest member of the elements of group 17 of the Periodic System (halogens). About 20 isotopes are known, and some of them have been identified as short-lived products in the natural radioactive series. The longest-lived isotope is 210At with a half-life of only 8.3 hours. Consequently, macroscopic quantities of this element cannot be accumulated. Our knowledge on its...

2005
Jun Tsuchiya, Taku Tsuchiya, Renata M. Wentzcovitch,

[1] Phonon dispersions and vibrational density of states of MgSiO3 postperovskite, the new high-pressure phase of MgSiO3 perovskite, are calculated as a function of pressure up to 180 GPa using density-functional perturbation theory. The calculated frequencies are then used to determine the thermal contribution to the Helmholtz free energy within the quasi-harmonic approximation. The equation o...

Journal: :Physical chemistry chemical physics : PCCP 2011
Fanica Cimpoesu, Seitaro Ito, Hidekazu Shimotani, Hidenori Takagi, Nita Dragoe,

Analysis of IR and Raman spectra of Ar@C(60) and Kr@C(60) shows that the incorporation of noble gas atoms causes a blue shift of low energy vibrations, which have radial character, and a red shift of higher energy ones which have a tangential character movement. The mechanism of these phenomena is explained on the basis of ab initio numerical experiments with DFT and MP2 procedures. Methodologi...

2008
Aditya M. Vora,

for the lattice constants i.e. 11 C , 12 C , 44 C , 44 12 C C − , 44 12 C C and bulk modulus B obtained using the Hartree (H) local field correction function has higher values in comparison with the results obtained for the same properties using Ichimaru-Utsumi (IU) local field correction function. The results for the Shear modulus ( C ′ ), deviation from Cauchy’s relation, Poisson’s ratio σ , ...

2008
Jun Tsuchiya, Taku Tsuchiya, RenaTa M. WenTzcoviTch,

We have performed first-principles calculations to investigate the behavior of the hydrogen bond in δ-AlOOH under pressure. The highest OH-stretching A1 and B2 mode frequencies decrease under pressure leading to hydrogen bond symmetrization. After hydrogen bond symmetrization, the corresponding frequencies gradually increase. This softening and subsequent hardening of the OH bonds is a good spe...