where the trajectory basis functions (TBFs) χJ k (R; RJ k (t), P J k (t), ᾱ) are defined 3N dimensional frozen Gaussians that evolve classically, i.e. their central position and momentum are propagated following Newton's equations of motion. Thus, a de-facto moving grid is created on the support of which the time-dependent Schrödinger equation is solved. Inserting this expansion into the TDSE allows to obtain evolution equations for the time-dependent coefficients as