title: Reduced dimensionality spin-orbit dynamics of CH3 + HCl ⇌ CH4 + Cl on ab initio surfaces.
abstract: A reduced dimensionality quantum scattering method is extended to the study of spin-orbit nonadiabatic transitions in the CH(3) + HCl ⇌ CH(4) + Cl((2)P(J)) reaction. Three two-dimensional potential energy surfaces are developed by fitting a 29 parameter double-Morse function to CCSD(T)/IB//MP2/cc-pV(T+d)Z-dk ab initio data; interaction between surfaces is described by geometry-dependent spin-orbit coupling functions fit to MCSCF/cc-pV(T+d)Z-dk ab initio data. Spectator modes are treated adiabatically via inclusion of curvilinear projected frequencies. The total scattering wave function is expanded in a vibronic basis set and close-coupled equations are solved via R-matrix propagation. Ground state thermal rate constants for forward and reverse reactions agree well with experiment. Multi-surface reaction probabilities, integral cross sections, and initial-state selected branching ratios all highlight the importance of vibrational energy in mediating nonadiabatic transition. Electronically excited state dynamics are seen to play a small but significant role as consistent with experimental conclusions.
authors.affiliation: Department of Chemistry, University of Oxford, PTCL, South Parks Road, Oxford OX13QZ, United Kingdom. smremmert@gmail.com
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Remmert
authors.forename: Simon T
authors.initials: ST
authors.lastname: Banks
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Harvey
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Orr-Ewing
authors.forename: David C
authors.initials: DC
authors.lastname: Clary