Convergence of vibrational angular momentum terms within the Watson Hamiltonian

Abstract

Vibrational angular momentum terms within the Watson Hamiltonian are often considered negligible or are approximated by the zeroth order term of an expansion of the inverse of the effective moment of inertia tensor. A multimode expansion of this tensor up to second order has been used to study the impact of first and second order terms on the vibrational transitions of N(2)H(2) and HBeH(2)BeH. Comparison with experimental data is provided. The expansion of the tensor can be exploited to introduce efficient prescreening techniques.

The PyPES library of high quality semi‐global potential energy surfaces

“…To verify that the PES’ within the PyPES library are implemented correctly, fundamental vibrational transition frequencies are calculated and compared with values from original publications. We used the vibrational configuration interaction (VCI) method, based upon the Watson operator in normal mode coordinates with zero rotational angular momentum, including Coriolis coupling through the leading term in the RSPT1 expansion of the vibrational angular momentum operator, and ignoring the Watson correction term . The wavefunction is expanded in a basis of harmonic oscillator functions in normal mode coordinates and all integrals are evaluated analytically.…”

Anharmonicities and coherent vibrational dynamics of phosphate ions in bulk H2O

“…The VCI treatment accounts for correlation effects of vibrational states beyond the VSCF mean field approach. All vibrational modes of the solute H 2 PO − 4 (15 modes) are included in the VCI/VSCF simulations [34][35][36][37][38][39] …”

Efficient Calculation of Multi-dimensional Potential Energy Surfaces of Molecules and Molecular Clusters

“…A 2nd order multimode expansion has been used for representing the vibrational angular momentum terms within the Watson Hamiltonian, i.e. the -tensor has been expanded accordingly (for details see [25]). …”