Multi-partitioning QDPT and difference-dedicated CI calculations of non-adiabatic couplings : Application to charge transfer in LiF system

Abstract

Potential energy and non-adiabatic coupling functions for the two lowest 1 Σ + states of LiF were calculated using the recently proposed perturbative approach, based on the multiple partitioning of the full Hamiltonian, and the difference-dedicated CI method. The results are compared with MRDCI and available full CI data for the same AO basis set. A high accuracy was achieved with a semiempirical perturbative scheme combining the direct calculations at second order with an approximate estimation of higher-order local contributions.