A new diabatization scheme for direct quantum dynamics: Procrustes diabatization

We present a new scheme for diabatizing electronic potential energy surfaces for use within the recently implemented direct-dynamics grid-based class of computational nuclear quantum dynamics methods, called Procrustes diabatization. Calculations on the well-studied molecular systems LiF and the butatriene cation, using both Procrustes diabatization and the previously implemented propagation and projection diabatization schemes, have allowed detailed comparisons to be made, which indicate that the new method combines the best features of the older approaches; it generates smooth surfaces, which cross at the correct molecular geometries, reproduces interstate couplings accurately, and hence allows the correct modeling of non-adiabatic dynamics.