Spin-Orbit Ab Initio Investigation of the Photodissociation of Dibromomethane in the Gas and Solution Phases

摘要

A clear and reliable theoretical investigation on dibromomethane (CHBr,) photodissociation is desired. The calculation must consider: (i) relativistic effects; (ii) the potential energy curves (PECs) of spin-orbit coupling states; (iii) geometry optimization by the method with both static and dynamic electron correlations; (iv) solvent effects oil the photodissociation in the solution. All these have been considered in this study by state-of-the-art quantum chemical calculations. The experimentally observed photodissociation in the gas phase with products of spin-orbit-coupled states, Br(P-2(3/2)) and Br*(P-2(1/2)), was assigned by multi-state second order multiconfigurational perturbation theory in conjunction with spin-orbit interaction through complete active space state interaction (MS-CASPT2/CASSI-SO) PECs. The mechanisms of the experimentally observed photodissociation and photoisomerization in solvent were elucidated by the MS-CASPT2/CASSI-SO method combined with polarized continuum model of the solvent. (C) 2008 Wiley Periodicals, Inc. J Comput Chem 29: 2513-2519, 2008