Structure and thermodynamic properties of Nickel-based superconducting matrix material [formula omitted

Abstract

The structure of different spatial groups of Nickel-based superconducting matrix material EuNi2Si2 is studied by using the Chen-Möbius lattice inversion potentials. In order to test the structural stability, some operations, such as energy minimization, shearing, stretching, random perturbation and X-ray diffraction spectra are operated. It is found that the structure of the spatial group number 139 has the lowest binding energy, and the structure is the most stable. In addition, we also calculate the phonon state density and thermodynamic properties of the stable structure of the spatial group number 139. For the phonon state density, the results suggest that the contribution of rare earth elements Eu and transition metal Ni with a large atomic mass is the greatest in the low frequency region, however, the contribution of elements Si with smaller atomic mass is more and more prominent with the increase of frequency. However, for the specific heat capacity and vibration entropy, the contributions of element Eu and Ni are larger in the low temperature region, and the contribution of element Si is more and more prominent with the temperature increasing.