Torsional Angle Definitions and Linear and Quadratic Force Field Variations along the Torsional Coordinate for CH3OH and CH3CHO

2002 ◽  
Vol 214 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Li-Hong Xu ◽  
Jon T. Hougen ◽  
Ronald M. Lees ◽  
Mirza A. Mekhtiev
Keyword(s):  
Force Field ◽  
Torsional Angle ◽  
Quadratic Force Field

Force field for in-plane vibrations of terephthalonitrile

1989 ◽  
Vol 54 (1) ◽  
pp. 18-27 ◽  
Author(s):  
Juan F. Arenas ◽  
Juan I. Marcos ◽  
Francisco J. Ramírez
Keyword(s):  
Experimental Data ◽  
Force Field ◽  
Normal Coordinates ◽  
Internal Coordinates ◽  
Isotopic Shifts ◽  
Quadratic Force Field ◽  
Semi Empirical

The general quadratic force field for the in-plane vibrations of terephthalonitrile was calculated by the semi-empirical MINDO/3 method. This force field was refined to the frequencies observed experimentally for terephthalonitrile and isotopic shifts of terephthalonitrile-[15N2]. The refined frequencies reproduce the experimental data with errors less than 0.5%. The normal coordinates and the force field in internal coordinates were also calculated from the refined field.

scholarly journals The Jahn–Teller effect in the presence of partial isotopic substitution: the B̃1E′′ state of NH2D and NHD2

2015 ◽  
Vol 17 (21) ◽  
pp. 14145-14158 ◽  
Author(s):  
Ashim Kumar Saha ◽  
Gautam Sarma ◽  
Chung-Hsin Yang ◽  
Sebastiaan Y. T. van de Meerakker ◽  
David H. Parker ◽  
...  
Keyword(s):  
Force Field ◽  
Field Model ◽  
Electronic States ◽  
Teller Effect ◽  
Isotopic Substitution ◽  
Quadratic Force Field ◽  
Jahn Teller ◽  
Jahn Teller Effect

A simple linear and quadratic force field model for the lifting of the degeneracy on asymmetric isotopic substitution in degenerate electronic states subject to a weak Jahn–Teller effect.

An ab initio quadratic force field for methyldiborane

1984 ◽  
Vol 23 (16) ◽  
pp. 2505-2509 ◽  
Author(s):  
David D. Keeports ◽  
David F. Eggers
Keyword(s):  
Force Field ◽  
Ab Initio ◽  
Quadratic Force Field

NORMAL MODES, CORIOLIS COUPLING, AND CENTRIFUGAL DISTORTION IN MOLECULES WITH NEARLY FREE INTERNAL ROTATION: CH3—C≡C—CH3 AND CH3—C≡C—SiH3

1967 ◽  
Vol 45 (12) ◽  
pp. 3867-3893 ◽  
Author(s):  
P. R. Bunker ◽  
J. T. Hougen
Keyword(s):  
Force Field ◽  
Internal Rotation ◽  
Energy Levels ◽  
Normal Modes ◽  
Force Constants ◽  
Coupling Constants ◽  
Torsional Angle ◽  
Coriolis Coupling ◽  
Centrifugal Distortion ◽  
Centrifugal Distortion Constants

In 1964 Duncan determined force fields for the molecules CH3—C≡C—CH3 and CH3—C≡C—SiH3 under the assumption that the force constants were not dependent on the torsional angle γ. In the first half of this paper we determine the quantitative effect of adding various γ-dependent force constants to Duncan's force field for CH3—C≡C—CH3. The results lead to complications concerning the symmetry species of the normal coordinates, the magnitude of the Coriolis coupling constants, and the calculation of the energy levels. The possible avoidance of these complications is discussed.In the second half of the paper a formalism is set up relating the rotational and torsional centrifugal distortion constants to the vibrational force field for certain molecules with nearly free internal rotation. Duncan's force field for CH3—C≡C—SiH3 is used to calculate some centrifugal distortion constants for that molecule and for CH3—C≡C—SiD3 on the assumption of completely free internal rotation. Good agreement is obtained between the quantities calculated here and the observed quantities determined by Kirchhoff and Lide.

Dichlorotrifluorophosphorane (PCl2F3): molecular structure by gas-phase electron diffraction and quadratic force field

1985 ◽  
Vol 24 (18) ◽  
pp. 2774-2777 ◽  
Author(s):  
Richard J. French ◽  
Kenneth Hedberg ◽  
Jeanne M. Shreeve ◽  
Krishna D. Gupta
Keyword(s):  
Molecular Structure ◽  
Electron Diffraction ◽  
Force Field ◽  
Gas Phase ◽  
Quadratic Force Field ◽  
Gas Phase Electron Diffraction
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