Include Nuclear Quantum Effects in Classical Molecular Dynamics

The accurate inclusion of nuclear quantum effects remains a big challenge for large-scale molecular simulations. We present an alternative formulation for the equations of motions of classical molecular dynamics with nuclear quantum effects included. With this new formulation, molecular dynamics simulations can be performed on an effective energy surface obtained from constrained energy minimization with assigned quantum nuclear expectation positions. We test the new molecular dynamics approach on the Morse oscillator and protonated water clusters and get significantly improved dynamical properties as compared to conventional molecular dynamics and ring-polymer molecular dynamics.