Nonadiabatic dynamics and simulation of time resolved photoelectron spectra within time-dependent density functional theory: Ultrafast photoswitching in benzylideneaniline

We present a theoretical approach for the nonadiabatic dynamics "on the fly" based on the combination of the time-dependent density functional theory (TDDFT) with Tully's stochastic surface hopping method. Our formulation is based on localized Gaussian basis sets and is suitable for the simulation of ultrafast processes in complex molecular systems including all degrees of freedom. Our approach is used for the simulation of time resolved photoelectron spectra in the framework of the Wigner distribution approach. In order to illustrate the scope of the method, we study the ultrafast photoswitching dynamics of the prototype Schiff base benzylideneaniline (BAN). The nonradiative lifetime of the S 1 state of BAN is determined to be ∼ 200 fs . The mechanism of the photoisomerization has been investigated and a connection between the time resolved photoelectron signal and the underlying nonadiabatic processes has been established.