title: Multistate, multichannel coupled diabatic state representations of adiabatic states coupled by conical intersections. CH2OH photodissociation.
abstract: A coupled diabatic state representation, Hd, of the 1, 2, 32A states of CH2OH suitable for the description of the three channel, three state photodissociation process CH2OH(12A) + hv → CH2OH(2, 32A) → CH2O(X, A) + H, cis-CHOH + H, trans-CHOH + H, is reported. The representation is based on electronic structure data (energies, energy gradients, and derivative couplings) obtained exclusively from multireference configuration interaction single and double excitation wave functions. Diabat shifting is employed to improve the representation's agreement with accurate experimental energetics. A careful analysis of the numerous minima, saddle points, and conical intersection seams is reported. The computed T0(32A) ∼ 35 220 cm-1is in excellent agreement with the experimental estimate of 35 053 cm-1, and the computed channel dissociation energies, D0, for CH2O 9453 (10 160), cis-HCOH 30 310.2 (29 923), and trans-HCOH 28 799 (28 391) cm-1are in good accord with the measured values given parenthetically. These accurate energetics over a wide range of nuclear configurations strongly support the ability of this Hdto enable quality simulations of nonadiabatic dynamics.
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Christopher L
authors.identifier: 0000000265537437
authors.initials: CL
authors.lastname: Malbon
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: David R
authors.identifier: 0000000254461350
authors.initials: DR
authors.lastname: Yarkony