Semiclassical Dynamics Simulation of the Photodissociation of Cyclobutane

Semiclassical electron-radiation-ion dynamics simulations are reported for the photodissociation of cyclobutane into two molecules of ethylene. The results clearly show the formation of the tetramethylene intermediate diradical, with dissociation completed in roughly 400 femtoseconds. In addition, the potential energy surfaces of the electronic ground state and lowest excited state were calculated at the CASSCF/MYPT2 level with 6-31G * basis sets, along the reaction path determined by the SERID simulations. There are well-defined energy minima and maxima in the intermediate state region. It is found that both C-C-C bond bending and rotation of the molecule (around the central C-C bond) play important roles in determining the features of the potential energy surfaces for the intermediate species. Finally, the simulations and potential energy surface calculations are employed together in a discussion of the full mechanism for cyclobutane photodissociation