Path integral molecular dynamics (PIMD) is a method of incorporating quantum mechanics into molecular dynamics simulations using Feynman path integrals.
The nuclei are treated quantum mechanically by mapping each quantum nucleus onto a classical system of several fictitious particles connected by springs (harmonic potentials) governed by an effective Hamiltonian, which is derived from Feynman's path integral.
There are now a number of commonly used condensed matter computer simulation techniques that make use of the path integral formulation including centroid molecular dynamics (CMD),[1][2][3][4][5] ring polymer molecular dynamics (RPMD),[6][7] and the Feynman–Kleinert quasi-classical Wigner (FK–QCW) method.
The first one is the non-Hamiltonian phase space analysis theory[15], which has been updated to create an "extended system" of isokinetic equations of motion which overcomes the properties of a system that created issues within the community.
PIMD is "widely used to describe nuclear quantum effects in chemistry and physics".