Molecular Force Fields of Some Selenium and Telurium Hexahalide Ions

1970 ◽  
Vol 25 (4) ◽  
pp. 566-569
Author(s):  
M. N. Avasthi ◽  
M. L. Mehta
Keyword(s):  
Matrix Method ◽  
Force Fields ◽  
Force Constants ◽  
Mean Amplitudes Of Vibration ◽  
Molecular Force

Abstract Wilson's GF matrix method has been used to evaluate all the seven independent force constants of some XY6 type ions using Müller's mathematical constraint. Mean amplitudes of vibration and Bastiansen-Morino shrinkages have also been calculated for these ions.

Molecular Force Fields of Some XY6 Type Ions of Oh Symmetry

1969 ◽  
Vol 24 (12) ◽  
pp. 2029-2030 ◽  
Author(s):  
M. N. Awasthi ◽  
M. L. Mehta
Keyword(s):  
Approximation Method ◽  
Matrix Method ◽  
Force Fields ◽  
Force Constants ◽  
Matrix Approximation ◽  
Mean Amplitudes Of Vibration ◽  
Fundamental Frequencies ◽  
Molecular Force

The L matrix approximation method has been applied to hexachlorides and hexabromides of Tin and Titanium of Oh symmetry. All the seven independent force constants have been evaluated using Wilson's G - F matrix method. Mean amplitudes of vibration have been computed using latest fundamental frequencies.

Harmonie Force Fields and Bond Orders for Naphthalene, Anthracene, Biphenylene and Perylene with Mean Amplitudes for Perylene

1978 ◽  
Vol 33 (1) ◽  
pp. 45-54 ◽  
Author(s):  
J. C. Whitmer ◽  
S. J. Cyvin ◽  
B. N. Cyvin
Keyword(s):  
Force Field ◽  
Force Fields ◽  
Field Approximation ◽  
Force Constants ◽  
Bond Orders ◽  
Mean Amplitudes Of Vibration ◽  
Complete Set ◽  
First Time ◽  
The Relationship ◽  
Good Agreement

Complete normal coordinate analyses were performed for naphthalene, anthracene, biphenylene and perylene, starting from a simple force field with seven adjustable force constants. A relationship between bond orders and carbon-carbon stretching force constants was deduced from: (a) bond distances as a function of bond orders, (b) a version of Badger's rule relating stretching force constants to the bond distances. The relationship was used to modify the initial seven-parameter force field, and the vibrational frequencies calculated from both the initial and modified force fields are discussed. In general the simple force field approximation produces sets of frequencies in remarkably good agreement with experimental assignments. The force field approximation failed badly when applied to benzene. No obvious explanation was found for this unexpected feature, which makes it worth while to continue the investigations. The mean amplitudes of vibration were calculated. For perylene an account of the complete set of mean amplitudes is given for the first time.

IV. 1,3,5,7-Cyclooctatetraene

1970 ◽  
Vol 25 (2) ◽  
pp. 134-138 ◽  
Author(s):  
M. Traetteberg ◽  
G. Hagen ◽  
S. J. Cyvin
Keyword(s):  
Vibration Analysis ◽  
Force Fields ◽  
Force Constants ◽  
Harmonic Vibration ◽  
Interatomic Distances ◽  
Mean Amplitudes Of Vibration ◽  
Amplitude Correction ◽  
Symmetry Coordinates

A harmonic-vibration analysis for the vibrations of 1,3,5,7-cyclooctatetraene was performed. A suitable set of symmetry coordinates is specified, and the corresponding symmetry force constants for C8H8 are given. The developed force fields were used to calculate mean amplitudes of vibration for C8H8 and C8D8. Calculated perpendicular amplitude correction coefficients for the various interatomic distances are also reported.

Force Field and Mean Amplitudes of Vibration of (NH2)2CX Compounds ( X = O, S, Se)

1982 ◽  
Vol 37 (11) ◽  
pp. 1289-1291
Author(s):  
Marcelo Campos ◽  
Guillermo Díaz
Keyword(s):  
Force Field ◽  
Matrix Method ◽  
Force Fields ◽  
Normal Coordinate Analysis ◽  
Vibrational Assignment ◽  
Normal Coordinate ◽  
Mean Amplitudes Of Vibration ◽  
Valence Force ◽  
Valence Force Field

Normal coordinate analysis of urea, thiourea and selenourea was performed on the basis of the general valence force field; Wilson’s FG matrix method has been used. The final force fields were obtained through an iterative selfconsistent method. The vibrational assignment for these molecules is discussed. Calculated mean amplitudes of vibration for the urea series and their deuterated derivatives are reported.

Vibrational frequencies, force constants, mean amplitudes, shrinkage effects, and Coriolis constants for CF3C≡CX (where X = Cl, Br, and I)

1973 ◽  
Vol 26 (2) ◽  
pp. 269 ◽  
Author(s):  
E Augdahl ◽  
E Kloster-Jensen ◽  
V Devarajan ◽  
SJ Cyvin
Keyword(s):  
Force Fields ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Coupling Constants ◽  
Coriolis Coupling ◽  
Harmonic Force ◽  
Mean Amplitudes Of Vibration

Harmonic force fields are developed for 1-chloro-, 1-bromo-, and 1- iodo-3,3,3-trifluoropropyne on the basis of recent infrared and Raman data. Calculated mean amplitudes of vibration, Bastiansen-Morino shrinkage effects, and Coriolis coupling constants are reported.

Molecular Force Fields of Tungsten and Uranium Hexachlorides

1972 ◽  
Vol 27 (4) ◽  
pp. 700-701 ◽  
Author(s):  
M.N. Avasthi ◽  
M.L. Mehta
Keyword(s):  
Force Field ◽  
Force Fields ◽  
Field Studies ◽  
Force Constants ◽  
Least Square ◽  
Valence Force ◽  
Valence Force Field ◽  
Weighted Least Square ◽  
Molecular Force ◽  
Molecular Force Field

Abstract Molecular force field studies of tungsten and uranium hexa-chloride have been carried out using the Urey-Bradley force field (UBFF) and the orbital valence force field (OVFF). Weighted least square adjustment has been used to fit the observed frequencies. Comments are also made on the suit-ability of the force fields used. The trends in stretching force constants have been discussed.

Pseudo-exact Force Constants for Tetramethyls of Group IVA Metals and Molecular Force Fields for Some Tetrahedral Molecules or Ions

1977 ◽  
Vol 32 (1) ◽  
pp. 76-78 ◽  
Author(s):  
A. K. Dublish ◽  
B. B. Srivastava ◽  
D. K. Sharma ◽  
U. P. Verma ◽  
A. N. Pandey
Keyword(s):  
Ir Spectra ◽  
Approximation Method ◽  
Force Fields ◽  
Vapour Phase ◽  
Force Constants ◽  
Approximation Methods ◽  
Mass Model ◽  
Molecular Force ◽  
Group Iva ◽  
Tetrahedral Molecules

Abstract Recently reported Coriolis constants of tetrahedral tetramethyls of group IVA metals from the vapour phase IR spectra have been used to determine the pseudo-exact force constants with the aid of the point mass model. The symmetrized force constants for tetramethyls of group IVA and some tetrahedral molecules and ions have also been computed following thhe L-F approximation method. The results are compared with exact or pseudo-exact force constants and with those force constants obtained from different approximation methods. The validity of the method has been tested.

scholarly journals A transferable active-learning strategy for reactive molecular force fields

2021 ◽  
Author(s):  
Tom Young ◽  
Tristan Johnston-Wood ◽  
Volker L. Deringer ◽  
Fernanda Duarte
Keyword(s):  
Machine Learning ◽  
Active Learning ◽  
Learning Strategy ◽  
Force Fields ◽  
Molecular Simulations ◽  
Quantum Mechanical ◽  
Interatomic Potentials ◽  
Molecular Force ◽  
High Level ◽  
Active Learning Strategy

Predictive molecular simulations require fast, accurate and reactive interatomic potentials. Machine learning offers a promising approach to construct such potentials by fitting energies and forces to high-level quantum-mechanical data, but...

Molecular force fields. Part XII.—Force constant relationships in the non-metallic hydrides

1950 ◽  
Vol 46 (0) ◽  
pp. 137-146 ◽  
Author(s):  
D. F. Heath ◽  
J. W. Linnett ◽  
P. J. Wheatley
Keyword(s):  
Force Constant ◽  
Force Fields ◽  
Molecular Force
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