The First Principle Study of Ni_2ScGa and Ni_2TiGa

摘要

We computed the electronic structure, elastic moduli, vibrational properties, and Ni_2TiGa and Ni_2ScGa alloys in the cubic L2_1 structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C_(11), C_(12) and C_(44). We calculated elastic constants in L2_1 structure for Ni_2TiGa and Ni_2ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and 5c 3d states for Ni_2TiGa, Ni 3d states and 5c 3d states for Ni_2ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni_2TiGa, 0.76 states/eV Cell for Ni_2ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2_1 phase is unstable since the phonon calculations have imagine modes.