MP2 hydration free energies of simple salts predicted through adaptive force matching

by Wang, Feng; Li, Jicun

The accuracy of a mol. dynamics simulation is determined by the underlying interaction model. Although electronic structure calculations can be very accurate, it is associated with a high computational cost, which severely limits its applicability for large systems. In order to address this challenge, the adaptive force matching (AFM) method has been developed that is capable of mapping an electronic structure potential energy surfaces to simple pair-wise energy expressions as used in standard mol. mechanics force fields. With only MP2 as reference, we have shown that force fields for various salts developed by AFM can reproduce the exptl. hydration free energies with an error less than 2%. The ion potentials also gave good dynamical properties, such as the diffusion constants We have also shown that cross terms from AFM can be used with traditional water potentials without seriously influencing the accuracy of the prediction. This opens up the possibility of combining AFM models with other existing models in large scale simulations.