Enhancement of energy decomposition analysis in fragment molecular orbital calculations

Energy decomposition analysis is one of the most attractive features of fragment molecular orbital (FMO) calculations from the point of view of practical applications. Here we report some enhancements for PIEDA in the ABINIT-MP program. One is a separation of the dispersion-type stabilization from the electron correlation energy, traditionally referred to as the "dispersion interaction" (DI). Another is an alternative evaluation of the electrostatic (ES) interaction using the restrained electrostatic potential (RESP) charges. The GA:CT stacked base pair and the Trp-Cage miniprotein were used as illustrative examples. The GA:CT stacked base pair is an illustrative example of two different types of interactions. One is the H-bond stabilized mainly by Electrostatic interaction and charge-transfer. The other is the stacking interaction dominated by dispersion. Our enhanced energy decomposition analysis helps to distinguish between the interaction types.image