Fourier path integral Monte Carlo study of a two-dimensional model quantum monolayer

Adsorption isotherms have been constructed for a 2-dimensional ²⁰Ne fluid that represents a quantum monolayer. A quantum distribution function theory is presented and implemented in the computation of the chemical potential as a function of the density of the adsorbed material. The quantum partition function in the canonical ensemble is written in its path integral representation with paths expanded in a Fourier series (Fourier path integral). The multidimensional integrals obtained in this representation are solved using the j-walking Monte Carlo integration technique. The results obtained suggest that as the quantum contributions increase the amount of adsorbed material decreases, compared with classical results. An increment in internal and kinetic energies due to quantum effects is responsible for the reduction in the amount of adsorbed material. As expected, quantum effects are much larger at low temperatures.