Thermal expansion calculated by Continuous Displacement Cluster Variation Method

Thermal expansion of a single component system in a two dimensional square lattice is calculated by employing Continuous Displacement Cluster Variation Method. It is demonstrated that the entropy effect arising from the freedom of local atomic displacements drives the thermal expansion. The coefficient of thermal expansion curve is compared with the one calculated based on Debye-Griineisen model within the quasi-harmonic approximation. The two curves demonstrate opposite behavior.