Photoexcited Ag ejection from a low-temperature He cluster: a simulation study by nonadiabatic Ehrenfest ring-polymer molecular dynamics

Abstract

Ring-polymer molecular dynamics (RPMD) simulations have been performed to understand the photoexcitation dynamics of an Ag atom embedded in a low-temperature cluster consisting of 500 helium atoms, after the electronic excitation 5p ²P_1/2 ← 5p ²S_1/2 and 5p ²P_3/2 ← 5p ²S_1/2 of the Ag atom. Along the RPMD trajectory the time evolution of electronic wavefunction within the spin–orbit ²P manifold is calculated, whereby the time-dependent Schrödinger equation and the RPMD equation of motion are coupled, using the à la Ehrenfest mean field approach. It is found from the simulations that the Ag atom is ejected from the helium cluster with the average time of 100 ps after photoexcitation with the average ejection velocity being 60–70 m s⁻¹, which is roughly in line with experiment. Meanwhile it is also found that the present simulations do not agree with experiment as to the final state of the ejected Ag atom.