A test-site method for the evaluation of the lattice-gas pressure in monte carlo simulations

Abstract

A new method for the evaluation of the lattice-gas pressure from Monte Carlo simulations is proposed and is illustrated for a square lattice with nearest-neighbour interactions. The method involves the determination of the derivative of the partition function with respect to the change in the total number of sites by using the removal or addition of a test site. Estimates of the lattice gas pressure by this test-site approach are compared with those obtained from the exact solution (for the halffilled lattice), the thermodynamic integration method, and the method of Meirovitch which involves the calculation of the pressure from the integral entropy. Both above and below the critical temperature the new method is found to work very well. It has the advantage of speed over the other methods and is, therefore, the most suitable for use in phase equilibrium calculations. ？ 1990 Taylor & Francis Ltd.