Improved potential energy surfaces of thioanisole and the effect of upper surface variations on the product distribution upon photodissociation

Electronically nonadiabatic photodissociation can be investigated in detail by experiments. This provides an opportunity to validate the current theory of electronically nonadiabatic processes, but is great challenge because the time scale of photodissociation processes can be long compared to the current capability for accurate direct dynamics simulations. To circumvent this difficulty, we have been using analytic diabatic potential energy matrices, such that the simulation time scale can be extended to the nanosecond region without neglecting the effects of external electron correlation. In previous work, we have developed full-dimensional three-state potential energy matrices for thioanisole photodissociation. In the current work, we extend this work in two main ways: (i) we improve the treatment of the initial torsional potential, and (ii) we shift the potential energy surfaces to investigate the quantitative effect on the dissociation lifetimes and product branching ratios of changing the energy and location of the S₁–S₂ conical intersection.