A new (multi-reference configuration interaction) potential energy surface for H2CO and preliminary studies of roaming.
We report a new global potential energy surface (PES) for H2CO, based on precise fitting of roughly 67 000 MRCI/cc-pVTZ energies. This PES describes the global minimum, thecis- andtrans-HCOH isomers, and barriers relevant to isomerization, formation of the molecular (H2+CO) and radical (H+HCO) products, and the loose so-called roaming transition-state saddle point. The key features of the PES are reviewed and compared with a previous PES, denoted by PES04, based on five local fits that are 'stitched' together by switching functions (Zhanget al.2004J. Phys. Chem. A108, 8980-8986 (doi:10.1021/jp048339l)). Preliminary quasi-classical trajectory calculations are performed at the total energy of 36 233 cm-1(103 kcal mol-1), relative to the H2CO global minimum, using the new PES, with a particular focus on roaming dynamics. When compared with the results from PES04, the new PES findings show similar rotational distributions, somewhat more roaming and substantially higher H2vibrational excitation.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.
Department of Chemistry, and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322, USA.
Xiaohong
X
Wang
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.|Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca, NY 14852, USA.
Paul L
PL
Houston
Department of Chemistry, and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322, USA jmbowma@emory.edu.
Joel M
http://orcid.org/0000-0001-9692-2672
JM
Bowman
RRKM theory; kinetics; quasi-classical trajectories; roaming; unimolecular reactions