Smart Monte Carlo algorithm for the adsorption of molecules at a surface

A modified grand canonical ensemble Monte Carlo (GCMC) technique has been d eveloped to simulate adsorption isotherms for molecules on or near a surfac e. The speed and accuracy of the simulation is increased by using a non-uni form distribution function, related to the force field exerted by the surfa ce and the current configuration, to generate coordinates for the creation of new particles in the simulation. With this method, isotherms are generat ed more efficiently than with current techniques in which the creation step relies on a uniform distribution to generate the coordinates of a new mole cule. This is shown by comparing the calculation of an isotherm for a simpl e molecule adsorbed on a graphite substrate from a traditional GCMC simulat ion with that calculated using this new technique.