Classical molecular dynamics (MD) simulations have been broadly used in biomolecular and material modeling for decades. The most important ingredient of the current force fields (FFs), atomic charge, remains fixed during MD simulations despite atomic environment changes. This crude approximation hinders the general applicability of the FF being used in multiple phases, such as gas, liquid, and crystal. Here we report our implementation of a geometry dependent charge flux (GDCF) model into the recently developed multipole-based AMOEBA+ polarizable potential. In this model, the charge flux is represented as a function of the geometrical deviation of bond and angle from their equilibria. A water model is parametrized starting from the previous AMOEBA+ water parameters (<i>J. Chem. Theory Comput.</i> 2019, 15, 4122). With AMOEBA+(CF) water, we show that similarly good quality of liquid thermodynamic, structural and dynamic properties is obtained as the previous AMOEBA+ water. Besides, in ambient conditions, the H-O-H angle can automatically change from 104.5° of an isolated monomer to ~106° of average angle in the liquid phase. Both the binding energy and interaction energy of water clusters agree excellently well with the CCSD(T)/CBS values. Finally, we show the general strategy of deriving GDCF parameters for common organic molecules and biomolecular fragments using <i>ab initio</i> data. The energy and force derivation of GDCF is based on the AMOEBA+ framework, but it can also be used by other FFs including fixed-charge and polarizable potentials in general.

Implementation of geometry dependent charge flux into multipole-based AMOEBA+ polarizable potential

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.