Detection of coherent electron dynamics in benzene and polycyclic aromatic hydrocarbons by two antiphase pulses: An ab initio study

The coherence of electron dynamics in medium-sized molecules was examined by real-time time-dependent density functional theory calculations coupled with molecular dynamics. We observed laser-pulse-induced oscillation of the dipole and an increase in the potential energy of the molecules studied (benzene, naphthalene, and anthracene). Moreover, the second laser pulse with an antiphase optical field oscillation suppressed the dipole oscillation by interference and reduced the potential energy of the molecules. This interference was not observed in a simulation that freezes ion motion. Thus, the photoinduced coherent beat was maintained for a finite time in large molecules, and here, we discuss the effects of the molecular size and the influence of temperature on the coherence preservation.