Yang-Yang (YY) and singular diameter critical anomalies arise in exactly soluble compressible cell gas (CCG) models that obey complete scaling with pressure mixing. Thus, on the critical isochore $\rho ={\rho }_c$, ${\tilde{C}}_{\mu }≔-T{d}^2\mu /d{T}^2$ diverges as $|t{|}^{-\alpha }$ when $t\propto T-T_c\to 0^{-}$ while ${\rho }_d-{\rho }_c\sim |t{|}^{2\beta }$ where ${\rho }_d(T)=\frac{1}{2}[{\rho }_{\text{liq}}+{\rho }_{\text{gas}}]$. When the discrete local CCG cell volumes fluctuate freely, the YY ratio ${\mathfrak{R}}_{\mu }={\tilde{C}}_{\mu }/C_V$ may take any value $-\infty <{\mathfrak{R}}_{\mu }<\frac{1}{2}$ but “anticorrelated” free volumes are needed for ${\mathfrak{R}}_{\mu }>0$. More general decorated CCGs, including “hydrogen bonding” water models, illuminate energy-volume coupling as relevant to ${\mathfrak{R}}_{\mu }$.

• Received 19 September 2015

DOI:https://doi.org/10.1103/PhysRevLett.116.040601