Determination of excess gibbs free energy of quantum mixtures by path integral Monte Carlo simulations

We report a new path integral method for calculating the difference in chemical potentials for a quantum mixture, which is a combination of the difference method and the ‘f−g’ method. The method is based on distribution functions of Active changes of paths of real particles in the system. We applied the new method to the isotopic mixture,³He +⁴He, at T = 2 K. The excess Gibbs free energy was computed over a range of compositions; the results are in relatively good agreement with experimental data. The method thus shows promise for further applications in the study of thermodynamic properties of dense quantum mixtures.