Due to the cuspidal ridges of adiabatic potential energy
surfaces
(PESs) and singularities of nonadiabatic couplings (NACs), obtaining
an analytical expression for the adiabatic Hamiltonian is difficult.
Thereby, nonadiabatic dynamics simulations are often carried out on-the-fly,
which is time-consuming. This motivates us to construct quasi-diabatic
representations, which have smooth PESs and diabatic couplings. In
this study, we propose a new quasi-diabatization method based on minimizing
derivative couplings (MDC) in a limited configuration space. The boundary
conditions are first considered and finally released to obtain the
adiabatic-to-diabatic rotation angles and transformation matrices.
As demonstrated in representative one- and two-dimensional models
and the widely studied linear H3 molecule, MDC performs
significantly better than the direct integration quasi-diabatization
approach. In particular, accurate diabatic potential energy matrices
have been successfully obtained even when the NACs of all configurations
in the considered space are nonnegligible.