# Including Quantum Effects in Molecular Simulations Using the Feynman–Kleinert Linearized Path Integral Method

## TL;DR

This paper reviews a method for including quantum effects in molecular simulations, focusing on the Feynman–Kleinert linearized path integral approach and its applications.

## Contribution

The paper provides a comprehensive review of the Feynman–Kleinert linearized path integral method and its applications in calculating quantum correlation functions.

## Key findings

- The Feynman–Kleinert linearized path integral method is effective for systems with many degrees of freedom.
- The method allows for the calculation of transport coefficients and other quantum properties.
- Comparisons with centroid and ring polymer molecular dynamics highlight its strengths and limitations.

## Abstract

During the last few decades, several approximate, but useful, methods for including dynamical quantum effects in molecular simulations have been developed. These methods can be applied to systems with hundreds of degrees of freedom and with arbitrary potentials. Among these methods, we find the Feynman–Kleinert linearized path integral model, including its planetary versions, which are the focus of this review. The aim is to calculate quantum correlation functions for complex systems. Many important properties, e.g., transport coefficients, may thus be obtained. We summarize important applications of the method, and compare them to alternative ones, such as centroid molecular dynamics and ring polymer molecular dynamics. We finally discuss possible future improvements of the FK-LPI method.