Density fluctuations and field mixing in the critical fluid

Abstract

Absiraei We develop a finite-suemaling theory describing the joint density and energy fluctuations in a near-mitical fluid. As a result of the mixing of the lemperalure and chemical potential in the WO relevant scaling fields, the energy operator features in the crilical density distribution as an antisymmetric mrrestion lo the Limiting ale-invariant form Both the limiling form and the correction am predicted to be fuaetions that are characteristic of lhe king universality dass, and am independently knom. The theory is tested with extensive Monte Carlo studies of lhe lvmdimensional LennardJones fluid, within the grand canonical ensemble. The simulations and sgling framework together are shown to prwide a powerful way of identifying lhe loCalion of lhe liquid-gas aitical point, while confirming and darimng its esenlially king charader. 'Ihe simulations also show a clearly identifiable signature of the rield-mixing responsible for the hilure of ihe law of rectilinear dismeler.