TEMPERATURE-DEPENDENCE OF ELASTIC-CONSTANTS OF EMBEDDED-ATOM MODELS OF PALLADIUM

The elastic constants of fcc palladium are calculated as a function of temperature for four different embedded-atom-method (EAM) models and compared to experimental values. Two of these EAM models have been derived by other workers whereas two of the models are new. Because of the elastic anomaly near 120 K, in the shear constant C44 of Pd, the use of this zero-temperature elastic constant to determine the Pd EAM potential leads to errors in the calculated C44 above the Debye temperature of 280 K where the potentials are to be used. To correct this behavior we determine the EAM potential in the two new EAM models so that C44 is in much better agreement with the experimental value above the Debye temperature. Interestingly in both of these new models the melting temperature is significantly higher and in better agreement with the experimental value of 1825 K. One of our models uses a conventional EAM third-neighbor interaction model whereas our other model is a fifth-neighbor interaction model.