Simulating Vibronic Spectra without Born–Oppenheimer Surfaces

We show how linear vibronic spectra in molecular systems can be simulated efficiently using first-principles approaches without relying on the explicit use of multiple Born–Oppenheimer potential energy surfaces. demonstrate and analyze performance mean-field beyond-mean-field dynamics techniques for H2 molecule one dimension, later case capturing structure quite accurately, including quantum Franck–Condon effects. In a practical application this methodology we simulate absorption spectrum benzene full dimensionality time-dependent density functional theory at multitrajectory Ehrenfest level, finding good qualitative agreement with experiment significant spectral reweighting compared to commonly used single-trajectory dynamics. These results form foundation nonlinear calculations promise future phenomena associated coupling more complex potentially condensed phase systems.