Making Peace\nwith Random Phases: Ab Initio Conical\nIntersection Quantum Dynamics in Random Gauges

Ab initio modeling of conical intersection wave packet\ndynamics\nis crucial for various photochemical, photophysical, and biological\nprocesses. However, adiabatic electronic states obtained from electronic\nstructure computations involve random phases, or more generally, random\ngauge fixings, which cannot be directly used in the modeling of nonadiabatic\nwave\npacket simulations. Here we develop a random-gauge local diabatic\nrepresentation that allows an exact modeling of conical intersection\ndynamics directly using the adiabatic electronic states with phases\nrandomly assigned during the electronic structure computations. Its\nutility is demonstrated by an exact ab initio modeling of the two-dimensional\nShin-Metiu model with and without an external magnetic field. Our\nresults provide a simple approach to integrating the electronic structure\ncomputations into nonadiabatic quantum dynamics, thus paving the way\nfor ab initio modeling of conical intersection dynamics.