Infrared intensities of amide modes in N‐methylacetamide and poly(glycine I) from ab initio calculations of dipole moment derivatives of N‐methylacetamide

1985 ◽  
Vol 82 (4) ◽  
pp. 1631-1641 ◽  
Author(s):  
T. C. Cheam ◽  
S. Krimm
Keyword(s):  
Dipole Moment ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Infrared Intensities ◽  
Derivatives Of

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1775-1781 ◽  
Author(s):  
Christopher D Daub ◽  
Bryan R Henry ◽  
Martin L Sage ◽  
Henrik G Kjaergaard
Keyword(s):  
Dipole Moment ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Moment Function ◽  
Polynomial Method ◽  
Small Contribution ◽  
Least Squares Regression ◽  
Vibrational Overtone ◽  
Moment Functions

Two studies of aspects of modelling dipole moment functions of XH bonds in small molecules for use in calculating overtone intensities have been undertaken. The first study deals with the fitting of ab initio calculations of the dipole moment at discrete points to a functional form. The two methods that are compared are the use of least-squares regression and the use of interpolating polynomials. The interpolating polynomial method is deemed superior due to its greater efficiency in terms of the number of points necessary to obtain reasonable results. The second study attempts to explain the indifference of calculated overtone intensities to the inclusion of electron correlation in the ab initio calculation of the dipole moment function. It is found that in most cases the influence of electron correlation can be modelled as a function with a very small matrix element, which results in a very small contribution to the overtone intensity.Key words: dipole moment function, vibrational overtone intensities, electron correlation, ab initio calculations.

Effective bond charges from infrared intensities: ab initio calculations

1996 ◽  
Vol 377 (1) ◽  
pp. 75-79 ◽  
Author(s):  
S. Ilieva ◽  
M. Krusteva ◽  
T. Dudev ◽  
B. Galabov ◽  
T. Gounev ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Infrared Intensities
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