Determination of molecular vibrational state energies using the ab initio semiclassical initial value representation: Application to formaldehyde

S.Y.Y. Wong1, D. Benoit2, M. Lewerenz, 3A. Brown1 and P.-N. Roy4

1Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada
2Nachwuchsgruppe Theorie, SFB 569, Albert-Einstein-Allee 11, University of Ulm, D-89081 Ulm, Germany
3Laboratoire Modelisation et Simulation, Multi Echelle (MSME FRE3160 CNRS), Université Paris Est (Marne-la-Vallée), Bâtiment Lavoisier, Cite Descartes, Champs sur Marne, 77454 Marne la Vallée Cedex 2, France
4Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

Abstract

We have demonstrated the use of ab initio molecular dynamics (AIMD) trajectories to compute the vibrational energy levels of molecular systems in the context of the semiclassical initial value representation (SC-IVR). A relatively low level of electronic structure theory (HF/3-21G) was used in this proof-of-principle study. Formaldehyde was used as a test case for the determination of accurate excited vibrational states. The AIMD-SC-IVR vibrational energies have been compared to those from curvilinear and rectilinear vibrational self-consistent field/vibrational configuration interaction with perturbation selected interactions-second-order perturbation theory (VSCF/VCIPSI-PT2) and correlation-corrected vibrational self-consistent field (cc-VSCF) methods. The survival amplitudes were obtained from selecting different reference wavefunctions using only a single set of molecular dynamics trajectories. We conclude that our approach is a further step in making the SC-IVR method a practical tool for first-principles quantum dynamics simulations.

Return to Dr. Alex Brown's Publications

This page maintained by alex.brown@ualberta.ca of the Department of Chemistry, University of Alberta

Last updated March 3, 2011.