Gaussian core model in two dimensions. I. Melting transition

The method of molecular dynamics computer simulation has been used to examine the solid–fluid transition for the Gaussian core model in two dimensions. The system contained 780 particles subject to periodic boundary conditions, and confined to a single reduced density p = 3−1/2. The virial pressure, mean potential energy, and pair correlation functions all indicate that the melting process is first order. However, the system is anomalous in that thermal expansivities of the solid and (low temperature) fluid phases are negative, and the density change on melting at constant pressure is positive.