Computing accurate and reliable thermodynamic properties of small molecules from MP2 and density functional theory with adaptive force matching

by Wang, Feng

Computing free energies and other ensemble properties with electronic structure methods are challenging due to the need to sample rough potential energy surface (PES) with many degrees of freedom. With the adaptive force matching (AFM) approach, electronic structure PES at MP2, LMP2, and DFT levels of theory is fitted to mol. mechanics energy expressions. The custom fit models from AFM are capable of predicting very accurate ensemble properties, such as hydration free energies (HFE), enthalpies of hydration, and diffusion constants B3LYP-D3(BJ) is shown to be sufficiently accurate with a triple-zeta quality basis set. With AFM, a few exptl. HFEs and enthalpy of hydration are flagged as problematic. A fragmentation method will be described that allows the method to be used on larger mols.