Fluctuation-based computer calculation of partial molar properties. II. A numerically accurate method for the determination of partial molar energies and enthalpies

A new operational definition of the partial molar energy is derived invoking the grand canonical ensemble formalism. This expression, used in conjunction with the fluctuation-explicit form of the Kirkwood-Buff relation for partial molar volumes, allows the accurate computer calculation of all mechanical partial molar properties in a multicomponent system. The method satisfies two independent consistency checks. Property values for all components in a mixture are obtained simultaneously, and the length of a simulation is independent of the number of species in the system.