Reproducing Quantum Probability Distributions at the Speed of Classical Dynamics: A New Approach for Developing Force-Field Functors

Modeling
nuclear quantum effects is required for accurate molecular
dynamics (MD) simulations of molecules. The community has paid special
attention to water and other biomolecules that show hydrogen bonding.
Standard methods of modeling nuclear quantum effects like Ring Polymer
Molecular Dynamics (RPMD) are computationally costlier than running
classical trajectories. A force-field functor (FFF) is an alternative
method that computes an effective force field that replicates quantum
properties of the original force field. In this work, we propose an
efficient method of computing FFF using the Wigner–Kirkwood
expansion. As a test case, we calculate a range of thermodynamic properties
of Neon, obtaining the same level of accuracy as RPMD, but with the
shorter runtime of classical simulations. By modifying existing MD
programs, the proposed method could be used in the future to increase
the efficiency and accuracy of MD simulations involving water and
proteins.