MULTI-PARTITIONING QDPT AND DIFFERENCE-DEDICATED CI CALCULATIONS OF NONADIABATIC COUPLINGS - APPLICATION TO CHARGE-TRANSFER IN LIF SYSTEM

Potential energy and non-adiabatic coupling functions for the two lowe st (1) Sigma(+) states of LiF were calculated using the recently propo sed perturbative approach, based on the multiple partitioning of the f ull Hamiltonian, and the difference-dedicated CI method. The results a re compared with MRDCI and available full CI data for the same AO basi s set. A high accuracy was achieved with a semiempirical perturbative scheme combining the direct calculations at second order with an appro ximate estimation of higher-order local contributions.