title: Hierarchical expansion of the kinetic energy operator in curvilinear coordinates for the vibrational self-consistent field method.
abstract: A new hierarchical expansion of the kinetic energy operator in curvilinear coordinates is presented and modified vibrational self-consistent field (VSCF) equations are derived including all kinematic effects within the mean field approximation. The new concept for the kinetic energy operator is based on many-body expansions for all G matrix elements and its determinant. As a test application VSCF computations were performed on the H(2)O(2) molecule using an analytic potential (PCPSDE) and different hierarchical approximations for the kinetic energy operator. The results indicate that coordinate-dependent reduced masses account for the largest part of the kinetic energy. Neither kinematic couplings nor derivatives of the G matrix nor its determinant had significant effects on the VSCF energies. Only the zero-point value of the pseudopotential yields an offset to absolute energies which, however, is irrelevant for spectroscopic problems.
authors.affiliation: Lehrstuhl für Theoretische Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Strobusch
authors.forename: Ch
authors.initials: Ch
authors.lastname: Scheurer