Ideal chemical potential contribution in molecular dynamics simulations of the grand canonical ensemble

An extended system Hamiltonian for the grand canonical ensemble that includes the number dependence of the ideal chemical potential is investigated. Use of the ideal contribution explicitly in the equations of motion provides simpler and more stable equations of motion than previous grand molecular dynamics methods. We find the equations of motion remain quite stable even in gaseous conditions where mean field treatments of the ideal contribution provide a trivial result. The equations of motion are solved in real variable space as opposed to using virtual variables. Application of this simulation method with a Lennard-Jones fluid in the gas, fluid and solid phases is demonstrated.