Ab initio multiple spawning dynamics of excited state intramolecular proton transfer: the role of spectroscopically dark states

Abstract

Excited state intramolecular proton transfer (ESIPT) and electronic relaxation in o-hydroxybenzaldehyde (OHBA) are simulated using ab initio multiple spawning (AIMS) dynamics, and the results are compared with those obtained for the closely related molecules malonaldehyde and methyl salicylate. The role of electronic state ordering (more specifically, the placement of spectroscopically dark states) is examined in the context of tautomerisation yield. When a state of nπ* character lies between the optically accessible state and S0, the extent of ESIPT is hindered.