Vibrational properties of surface hydroxyls: Nonempirical model calculations including anharmonicities

1988 ◽  
Vol 53 (10) ◽  
pp. 2191-2202 ◽  
Author(s):  
Hartmut Mix ◽  
Joachim Sauer ◽  
Klaus-Peter Schröder ◽  
Angela Merkel
Keyword(s):  
Vibrational Analysis ◽  
Numerical Differentiation ◽  
Force Constants ◽  
Basis Set ◽  
Vibrational Properties ◽  
Model Calculations ◽  
Normal Coordinates ◽  
Theory Comparison ◽  
Surface Hydroxyls ◽  
Anharmonicity Constants

Complete sets of harmonic, semidiagonal cubic as well as diagonal cubic and quartic force constants are reported for the internal coordinates of terminal, ≣SiOH, and bridging, ≣SiOH·Al≣, surface hydroxyls on silica and zeolites. They are obtained by numerical differentiation of analytically calculated gradients of the energy (SCF approximation, 6-31 G* basis set). A GF vibrational analysis is performed and after making a nonlinear transformation of the force constants into normal coordinates the anharmonicity constants are evaluated by perturbation theory. Comparison is made with the D2OH+ ion and the DOH molecule. The calculated anharmonicities of the OH bonds in the systems studied are remarkably constant and vary between -76 and -84 cm-1, only in agreement with the values observed for DOH (-83 cm-1) and surface silanols, ≣SiOH (-90 ± 15 cm-1).

Infrared spectrum, potential constants, and structure of thio-thionyl fluoride

1965 ◽  
Vol 18 (5) ◽  
pp. 627 ◽  
Author(s):  
RD Brown ◽  
GP Pez ◽  
MF O'Dwyer
Keyword(s):  
Electronic Structure ◽  
Infrared Spectrum ◽  
Thermodynamic Functions ◽  
Vibrational Analysis ◽  
Force Constants ◽  
Normal Coordinate ◽  
Infrared Data

An investigation of the infrared spectrum of gaseous thio-thionyl fluoride (SSF2) results in the following assignment of fundamentals: A': v1 760.5�0.2cm-1, v2 718.5�0.2 cm-1, v3 411.2�0.4cm-1, v4 364.1�0.3 cm-1. A": v5 692.3�0.8cm-1, v6 337.6�0.4 cm-1. A normal coordinate vibrational analysis has been performed and a set of ten force constants evaluated. Some conclusions are given regarding the electronic structure of SSF2. Thermodynamic functions based on the usual assumptions have been calculated for SSF2. A set of potential constants has been evaluated for disulphur monoxide, SSO, using the available infrared data.

scholarly journals Lattice Dynamics of Simple Harmonic and Anharmonic Shell Models

1967 ◽  
Vol 20 (5) ◽  
pp. 495 ◽  
Author(s):  
J Oitmaa
Keyword(s):  
Dipole Moment ◽  
Shell Model ◽  
Lattice Dynamics ◽  
Higher Order ◽  
Force Constants ◽  
Dynamical Equations ◽  
Normal Coordinates ◽  
Shell Models ◽  
Rigid Ion Model ◽  
Explicit Expressions

The lattice dynamics of harmonic and anharmonic shell models are reviewed. It is shown that the various dynamical equations for the shell model can be expressed in the same form as those for the rigid ion model, but with modified force constants. The anharmonic shell model leads to higher order contributions to the dipole moment, quadratic and cubic in the normal coordinates, for which explicit expressions are obtained.

Notizen:Schwingungseigenschaften des TeO42- -Ions/ Vibrational Properties of the TeO42--Ion

1978 ◽  
Vol 33 (10) ◽  
pp. 1226-1227
Author(s):  
Enrique J. Baran
Keyword(s):  
Force Field ◽  
Related Species ◽  
Force Constants ◽  
Vibrational Properties ◽  
Bond Orders ◽  
Mean Amplitudes Of Vibration ◽  
Valence Force ◽  
Valence Force Field ◽  
Complete Assignment

Abstract A complete assignment of the fundamental vibrations of the tetrahedral TeO42- ion is proposed and its principal force constants have been calculated using the modified valence force field. Mean amplitudes of vibration and bond orders are also estimated. The results are briefly discussed and some comparisons with related species are made.

Electronic Structure, Nonlinear Optical Properties, and Vibrational Analysis of Ethyl benzoate by Density Functional Theory

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Tanveer Hasan ◽  
P. K. Singh
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Ethyl Benzoate ◽  
Computational Method ◽  
Basis Set ◽  
Vibrational Modes ◽  
Normal Coordinate ◽  
Functional Theory ◽  
Vibrational Bands

This work deals with the vibrational spectroscopy of Ethyl benzoate (C9H10O2). The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) using standard HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods and basis set combinations. The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes.

Notizen: Schwingungseigenschaften und thermodynamische Funktionen von Mn2O7

1987 ◽  
Vol 42 (3) ◽  
pp. 307-309 ◽  
Author(s):  
Enrique J. Baran
Keyword(s):  
Thermodynamic Functions ◽  
Related Species ◽  
Molecular Model ◽  
Force Constants ◽  
Vibrational Properties ◽  
Mean Amplitudes Of Vibration ◽  
Infrared Data

Vibrational Properties and Thermodynamic Functions of Mn2O7The main force constants for Mn2O7 have been calculated from recently reported infrared data, using a simplified molecular model. Mean amplitudes of vibration and thermodynamic functions are also reported. The results are briefly discussed and some comparisons with related species are made.

Sign in / Sign up

Export Citation Format

Share Document