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

S. Y. Y. Wong (1) , D. M. Benoit (2) , Marius Lewerenz (3) , A. Brown (1) , P.-N. Roy (4)

1 University of Alberta
2 Nachwuchsgruppe Theorie, SFB 569
3 MSME - Laboratoire de Modélisation et Simulation Multi Echelle
4 Department of Chemistry [Waterloo]

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.

Domaines: Chimie théorique et/ou physique

S. Y. Y. Wong, D. M. Benoit, Marius Lewerenz, A. Brown, P.-N. Roy. Determination of molecular vibrational state energies using the ab initio semiclassical initial value representation: Application to formaldehyde. Journal of Chemical Physics, 2011, 134, pp.094110. ⟨10.1063/1.3553179⟩. ⟨hal-00830365⟩