On vibrational force field calculations

1991 ◽  
Vol 69 (11) ◽  
pp. 1672-1678 ◽  
Author(s):  
W. F. Murphy
Keyword(s):  
Force Field ◽  
Key Words ◽  
Force Fields ◽  
Vibrational Frequencies ◽  
Direct Access ◽  
Force Field Calculations ◽  
Harmonic Force ◽  
Normal Coordinate ◽  
Current Generation

A series of computer routines for performing normal coordinate calculations of harmonic vibrational frequencies is described. These are designed for operation on current-generation computers having direct-access storage. Example results are given for the chain isomer of disulfur difluoride. Key words: vibrational force field calculations, normal coordinate calculations, harmonic force fields.

Harmonic Force Field and Mean Amplitudes for C4Cl4 and C4F4 Compounds

1982 ◽  
Vol 37 (11) ◽  
pp. 1292-1294 ◽  
Author(s):  
G. Díaz
Keyword(s):  
Force Field ◽  
Vibrational Frequencies ◽  
Vibrational Assignment ◽  
Harmonic Force ◽  
Normal Coordinate ◽  
Coordinate Treatment

Normal coordinate treatment of C4F4 and C4Cl4 in the GVFF was performed using published vibrational frequencies. The vibrational assignment for these molecules is discussed. Calculated mean amplitudes for both molecules are reported.

Comparison of STO-3G and 3-21G ab initio harmonic force fields for ethane, propane, dimethyl ether, and cyclobutane: effects of geometry and scaling on calculated frequencies, eigenvectors, and infrared absorption intensities

1988 ◽  
Vol 66 (5) ◽  
pp. 1318-1332 ◽  
Author(s):  
R. Anthony Shaw ◽  
Charles Ursenbach ◽  
Arvi Rauk ◽  
Hal Wieser
Keyword(s):  
Force Field ◽  
Ab Initio ◽  
Dimethyl Ether ◽  
Infrared Absorption ◽  
Force Fields ◽  
Vibrational Frequencies ◽  
Harmonic Force ◽  
Scaling Factors ◽  
Bond Lengths ◽  
Optimized Geometries

Ab initio harmonic force fields were calculated for ethane, propane, dimethyl ether, and cyclobutane at the STO-3G and 3-21G levels. The calculated frequencies, displacement eigenvectors, and calculated infrared absorption intensities were compared as they derive from force constants that were (i) unsealed; (ii) scaled to fit observed vibrational frequencies reported in the literature; (iii) evaluated at the optimized geometries; and (iv) evaluated at structures for which the bond lengths were corrected from the optimized geometries according to published procedures. A total of nine combinations of ab initio force field/reference geometry/G-matrix geometry were investigated for each of the four molecules. The ability of scaling factors as the only variables to predict vibrational parameters from STO-3G and 3-21G force fields was explored. Conditions were examined for which the scaling factors are satisfactorily transferable among different molecules.

Synthèse, structure et études spectroscopiques RMN 1H et 13C de dérivés perhydrocyclododéca[b]furaniques

1991 ◽  
Vol 69 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Michel Albrand ◽  
René Dolmazon ◽  
Patrick Pollet
Keyword(s):  
Conformational Analysis ◽  
Force Field ◽  
Key Words ◽  
Molecular Mechanics ◽  
Trans Isomer ◽  
Nmr Spectra ◽  
Synthetic Route ◽  
Force Field Calculations ◽  
Cis Isomer ◽  
C Nmr

A synthetic route to perhydrocyclododeca[b]furan-3-ols, perhydrocyclododeca[b]furan-3-ones, and perhydrocyclododeca[b]furan derivatives is described. Their configurations were determined. For the perhydrocyclododeca[b]furan-3-one and perhydrocyclododeca[b]furan pairs, the cis isomer was much less stable than the trans isomer. This agrees well with results from a conformational analysis, carried out by molecular mechanics. The 1H and l3C NMR spectra are reported. Key words: perhydrocyclododeca[b]furans, conformations, force field calculations, 1H and 13C NMR.

Multiphoton ionization photoelectron spectroscopy of phenol: Vibrational frequencies and harmonic force field for the 2B1 cation

1985 ◽  
Vol 82 (12) ◽  
pp. 5329-5339 ◽  
Author(s):  
Scott L. Anderson ◽  
Lionel Goodman ◽  
Karsten Krogh‐Jespersen ◽  
Ali G. Ozkabak ◽  
Richard N. Zare ◽  
...  
Keyword(s):  
Force Field ◽  
Photoelectron Spectroscopy ◽  
Multiphoton Ionization ◽  
Vibrational Frequencies ◽  
Harmonic Force
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