Asymmetric fluid criticality. II. Finite-size scaling for simulations

The vapor-liquid critical behavior of intrinsically asymmetric fluids is studied in finite systems of linear dimensions L focusing on periodic boundary conditions, as appropriate for simulations. The recently propounded ``complete'' thermodynamic (→L∞) scaling theory incorporating pressure mixing in the scaling fields as well as corrections to scaling [Phys. Rev. E 67, 061506 (2003)] is extended to finite $L,$ initially in a grand canonical representation. The theory allows for a Yang-Yang anomaly in which, when →L∞, the second temperature derivative (d²μ_σ/dT²) of the chemical potential along the phase boundary μ_σ(T) diverges when →TTc-. The finite-size behavior of various special critical loci in the temperature-density or (T,ρ) plane, in particular, the k-inflection susceptibility loci and the Q-maximal loci --- derived from QL(T,〈ρ〉L)≡〈m²〉L²/〈m⁴〉L where m≡ρ-〈ρ〉L --- is carefully elucidated and shown to be of value in estimating Tc and ρc. Concrete illustrations are presented for the hard-core square-well fluid and for the restricted primitive model electrolyte including an estimate of the correlation exponent ν that confirms Ising-type character. The treatment is extended to the canonical representation where further complications appear.