The multistate Bennett acceptance ratio (MBAR) and unbinned weighted histogram analysis method (UWHAM) are widely used approaches to calculate free energies of multiple thermodynamical states. MBAR/UWHAM has several advantages comparing to the traditional WHAM method and is routinely used in alchemical free energy calculations, umbrella sampling, and temperature/Hamiltonian replica exchange simulations to calculate relative free engines and potentials of mean force (PMF).
FastMBAR is a solver written in Python to solve large scale MBAR/UWHAM equations. It can use both CPUs and GPUs. To learn more about FastMBAR, please read the documentations at https://fastmbar.readthedocs.io