Core Electron Energies, Infrared Intensities, and Atomic Charges

1997 ◽  
Vol 119 (18) ◽  
pp. 4224-4231 ◽  
Author(s):  
Paulo H. Guadagnini ◽  
Anselmo E. Oliveira ◽  
Roy E. Bruns ◽  
Benicio de Barros Neto
Keyword(s):  
Atomic Charges ◽  
Core Electron ◽  
Infrared Intensities

scholarly journals Unavoidable Failure of Point Charge Descriptions of Electronic Density Changes for Out-of-Plane Distortions

2021 ◽  
Author(s):  
Wagner Richter ◽  
Leonardo J. Duarte ◽  
Roy E. Bruns
Keyword(s):  
Point Charge ◽  
Degrees Of Freedom ◽  
Chemical Information ◽  
Atomic Charges ◽  
Electronic Density ◽  
Population Analyses ◽  
Out Of Plane ◽  
Planar Molecules ◽  
Equilibrium Structures ◽  
Infrared Intensities

<div>Population analyses based on point charge approximations accurately estimating the equilibrium dipole moment will systematically fail when predicting infrared intensities of out-of-plane vibrations of planar molecules, whereas models based on both charges and dipoles will always succeed. It is not a matter of how the model is devised, but on its number of degrees of freedom. Population analyses based on point charges are very limited in terms of the amount of meaningful chemical information they provide, whereas models employing both atomic charges and atomic dipoles should be preferred for molecular distortions. A good model should be able to correctly describe not only static, equilibrium structures but also distorted geometries in order to correctly assess information from vibrating molecules. The limitations of point charge models also hold for distortions much larger than those encountered vibrationally.</div>

scholarly journals Unavoidable Failure of Point Charge Descriptions of Electronic Density Changes for Out-of-Plane Distortions

2021 ◽  
Author(s):  
Wagner Richter ◽  
Leonardo J. Duarte ◽  
Roy E. Bruns
Keyword(s):  
Point Charge ◽  
Degrees Of Freedom ◽  
Chemical Information ◽  
Atomic Charges ◽  
Electronic Density ◽  
Population Analyses ◽  
Out Of Plane ◽  
Planar Molecules ◽  
Equilibrium Structures ◽  
Infrared Intensities

<div>Population analyses based on point charge approximations accurately estimating the equilibrium dipole moment will systematically fail when predicting infrared intensities of out-of-plane vibrations of planar molecules, whereas models based on both charges and dipoles will always succeed. It is not a matter of how the model is devised, but on its number of degrees of freedom. Population analyses based on point charges are very limited in terms of the amount of meaningful chemical information they provide, whereas models employing both atomic charges and atomic dipoles should be preferred for molecular distortions. A good model should be able to correctly describe not only static, equilibrium structures but also distorted geometries in order to correctly assess information from vibrating molecules. The limitations of point charge models also hold for distortions much larger than those encountered vibrationally.</div>

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