Alder-Hoover-Young hard disk equation of state

The Alder-Hoover-Young hard disk equation of state is given by (Ref. 1 Eq. 1)

$Z=\frac{pV}{N{k}_{B}T}=\frac{D}{\alpha }+C_0+C_1\alpha$

where Z is the compressibility factor, $C_0=1.90\pm 0.01$ and $C_1=0.67\pm 0.07$ and $D$ is the dimensionality of the system, i.e. for hard disk $D=2$.

$\alpha =\frac{V-V_0}{V_0}$

where $V_0$ is the close packed volume.

References

1. B. J. Alder, W. G. Hoover, and D. A. Young "Studies in Molecular Dynamics. V. High-Density Equation of State and Entropy for Hard Disks and Spheres", Journal of Chemical Physics 49 pp. 3688-3696 (1968)