A study of low temperature heat capacity anomalies in bimetallic alloy clusters using J-walking Monte Carlo methods

Abstract

Heat capacities are calculated as a function of temperature for bimetallic clusters composed of six palladium and seven nickel atoms using Monte Carlo techniques both with and without J‐walking. By applying a simulated annealing strategy, the minimum energy configurations at 0 K are identified for a series of interatomic interaction strengths. A significant dependence of the spatial arrangement of atoms on the strength of the Pd–Ni interaction is observed. Calculations of the heat capacity as a function of temperature show the presence of a ‘‘melting’’ coexistence region similar to that observed in pure clusters. For the alloy clusters, low temperature heat capacity anomalies are observed arising from isomerizations that are reminiscent of order–disorder transitions known to occur in some bulk alloy materials. These low temperature heat capacity anomalies are observable only when the J‐walking algorithm is used.