Continuous fractional component Monte Carlo: An adaptive biasing method for open system atomistic simulations

A new open system Monte Carlo procedure designed to overcome difficulties with insertion and deletion of molecules is introduced. The method utilizes gradual insertions and deletions of molecules through the use of a continuous coupling parameter and an adaptive bias potential. The method draws upon concepts from previous open system molecular dynamics and expanded ensemble Monte Carlo techniques and is applied to both the grand canonical and osmotic ensembles. It is shown to yield correct results for the volumetric properties of the Lennard-Jones fluid and water as well as the phase behavior of the CO2-ethanol binary system.