κSE. The SE method in an adiabatic basis involves an expansion of the electronic wave function in an N-state basis: (11) where is the coefficient of adiabatic electronic state . Inserting eq 11 into the time dependent electronic Schrödinger equation, using eqs 5 and 6 for the TDC, and performing some straightforward calculus gives the electronic equation of motion (EOM) for κSE: