Ab initio reaction pathways for photodissociation and isomerization of nitromethane on four singlet potential energy surfaces with three roaming paths

作者：Isegawa Miho^*; Liu Fengyi; Maeda Satoshi; Morokuma Keiji

来源：Journal of Chemical Physics, 2014, 140(24): 244310.

DOI：10.1063/1.4883916

Photodissociation pathways of nitromethane following pi -%26gt; pi* electronic excitation are reported. The potential energy surfaces for four lowest singlet states are explored, and structures of many intermediates, dissociation limits, transition states, and minimum energy conical intersections were determined using the automated searching algorism called the global reaction route mapping strategy. Geometries are finally optimized at CASSCF(14e, 11o) level and energies are computed at CAS(14o, 11e) PT2 level. The calculated preferable pathways and important products qualitatively explain experimental observations. The major photodissociation product CH3 and NO2 (B-2(2)) is formed by direct dissociation from the S-1 state. Important pathways involving S-1 and S-0 states for production of various dissociation products CH3NO + O (D-1), CH3O((XE)-E-2) + NO (X-2 Pi), CH2NO + OH, and CH2O + HNO, as well as various isomerization pathways have been identified. Three roaming processes also have been identified: the O atom roaming in O dissociation from CH3NO2, the OH radical roaming in OH dissociation from CH2N(O)(OH), and the NO roaming in NO dissociation from CH3ONO.

• 出版日期2014-6-28