Ross melting rule

The Ross melting rule states (Eq. 4 ):

$A=\frac{1}{2}NE(0)-N{k}_{B}T\ln \upsilon -N{k}_{B}T\ln \underset{f}{\overset{*}{\upsilon }}$

where $A$ is the Helmholtz energy function, $N$ is the number of cells, $E(0)$ is the potential at the centre of the cell, $k_B$ is the Boltzmann constant, $T$ is the temperature, $\upsilon$ is the volume of the cell, and $\underset{f}{\overset{*}{\upsilon }}$ is the dimensionless reduced volume in configuration space.