Abstract: Structure parameters, magnetic moments, tetragonal distortions and magnetic microcosmic mechanisms of single crystal Ni₂MnGa Heusler alloy were studied by the vienna abinitio simulation package (VASP). The results show that the structure parameters and magnetic moments agree well with the available experimental data and are better than the local spin density approximation (LSDA) method results compared with the available experiment data and other theoretical values. By analyzing tetragonal distortions, there exists a sharp minimum value near c/a=1 and a local maximum value at c/a≈0.94, and this maximum value corresponds to a stable martensitic phase. In addition, the variation of the total magnetic moment with c/a is mainly due to the contribution of Ni atoms because the total magnetic moment is almost equally contributed by two Ni atoms of per formula unit, while the contribution of Mn atom is very small. By analyzing the total state density (DOS) of alloy, the state densities of major peaks at the majority spin states are below the Fermi level. At the minority spin states, the two major peaks are separated by the Fermi level, which is the characteristic of stability for ferromagnetic ordered alloys. The magnetism of Ni₂MnGa alloy mainly originates from Mn atom, and the Mn moment in Ni₂MnGa originates from its d-e_g and d- t_2g sub-bands, which agrees with the experimental results.

Key words: Ni₂MnGa; magnetic microcosmic mechanism; states density; first-principle