Effects of different initial condition samplings on photodynamics and spectrum of pyrrole

Abstract

Semiclassical simulations of spectrum and dynamics of complex molecules require statistical sampling of coordinates and momenta. The effects of using thermal and quantum samplings are analyzed taking pyrrole as a test case. It is shown that there are significant differences in the results obtained with each of these two approaches. Overall, quantum sampling based on a Wigner distribution renders superior results, comparing well to the experiments. Dynamics simulations based on surface hopping and ADC(2) reveal that pyrrole internal conversion to the ground state occurs not only through H‐elimination path, but also through ring‐distortion paths, which have been systematically neglected by diverse experimental setups. The analysis of the reaction paths also shows that the ionization potential varies by more than 5 eV between ionization of the excited state at the Franck–Condon region and at the intersections with the ground state. This feature may have major implications for time‐resolved photoelectron spectroscopy. © 2015 Wiley Periodicals, Inc.