Ab. Mccoy, COMPARISON OF SELF-CONSISTENT-FIELD TREATMENTS OF KINETIC COUPLINGS IN CALCULATIONS ON POLYATOMIC-MOLECULES, Chemical physics letters, 293(1-2), 1998, pp. 103-109
The accuracy of the vibrational self-consistent field (VSCF) and time-
dependent self-consistent field (TDSCF) approximations for studies of
vibrational dynamics of polyatomic systems is investigated for systems
in which the most important off-diagonal coupling terms in the Hamilt
onian are in the kinetic energy operator. To lowest order, these terms
are zero in the VSCF treatment. This leads to large differences betwe
en the energies calculated using this approximation, compared to those
obtained from a variational calculation. In contrast, the energy leve
ls, obtained using the TDSCF approximation, are in good agreement with
variational results. These questions are investigated using a colline
ar model of HCN in an internal coordinate representation. (C) 1998 Els
evier Science B.V. All rights reserved.