An Abinitio Study of Nitrous-Acid - Geometries, Force-Constants, Fundamental Frequencies, and Potential Surface for Cis-Trans Isomerization

by Coffin, James Michael; Pulay, Peter

The geometries, quadratic force fields, and fundamental vibrational frequencies of cis- and trans-nitrous acid have been determined by using local fourth-order Moller-Plesset perturbation theory, and also two-pair generalized valence bond wave functions. The Hartree-Fock approximation is inadequate for this molecule, due to strong electron correlation. The theoretical force field for the trans isomer agrees, after scaling, very well with the experimental values of Deeley and Mills. The experimental force field of the cis isomer is less accurately known and the present results are probably the most reliable date available. The energies and force constants along the cis-trans isomerization path have been determined for future studies of the dynamics of the isomerization reaction.

Journal
Journal of Physical Chemistry
Volume
95
Issue
1
Year
1991
Start Page
118
ISBN/ISSN
1520-5215; 0022-3654
DOI
10.1021/j100154a027