Ferreira M. M. C., “INTERPRETATION OF INFRARED INTENSITIES BASED ON THE ATOMIC POLAR TENSOR PARTITION. THE ROH MOLECULES (R=H, CH₃, NH₂OH, F)”. Dresden, Democratic Republic of Germany, 04-08/09/1989: XIXth European Congress on Molecular Spectroscopy (EUCMOS XIX), Abstracts of lectures and poster contributions, 113 (1989). Poster P 36.

INTERPRETATION OF INFRARED INTENSITIES BASED
ON THE ATOMIC POLAR TENSORS PARTITION.
THE ROH MOLECULES (R = H, OH, CH₃, F)

M. M. C. Ferreira
Instituto de Quimica, Unicamp, Campinas-SP-13081 Brazil

The  Atomic  Polar  Tensor   (APT)    (gradient  of   the   dipole   moment   vector)
for atom  a,  is  directly  related   to  the  IR  intensities  of  molecules  in  the gas
phase.  It  can  be  theoretically  calculated  for  a  molecule  with  A atoms by  the
expression

where  q_a  is Mulliken's  net atomic charge,  E  is the (3×3) identity matrix,  R_a  is
the vector position of atom a and   P_mn   is a density matrix element.  The  integrals
over  the  basis functions give  the  distance from  the  center ofelectronic charge
for the hybrid  mn  orbital to the respective  nuclei  (atomic contribution),  or  to  the
center of the chemical bond in the case which m  belongs to A and n  to  B  (bond-
ing  contribution).  These  contributions  can  be  rearranged  for  interpretation  in
terms of  a  "charge",  "charge-flux"  model.  The  OH  bond will be studied  for  the
series of ROH where R = H, OH, F, CH₃ based on the partition of  the APT for the
H  atom  calculate  by  the  ab-initio  method  using  4-31  G  basis  set.
 
 
 
 
 
 

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