Heusler合金Ni2MnGa马氏体相变微观电子结构机理的研究
The study of mechanism of microcosmic electronic structure of martensitic transformation in Heusler alloy Ni2MnGa

采用基于密度泛函理论的第一性原理框架下的投影扩充波函数（PAW）方法，研究了Heusler合金Ni2MnGa马氏体相变的微观电子结构机理．结果表明：Ni2MnGa发生马氏体相变时，其晶体发生了自正八面体结构朝 轴拉长型八面体结构的畸变．此畸变源自于由Ni的 轨道电子的非均匀排布所引发的强带Jahn？CTeller效应，其发生的机制是：通过孤对电子由 轨道转移到 轨道，导致 方向的配体内移， 方向的配体外移，从而使 、 能级升高，及 、 、 能级降低，消除和降低能级的简并度，体系能量降低，体系畸变到一个更稳定的状态（马氏体相）．
The mechanism of microcosmic electronic structure of martensitic transformation in Heusler alloy Ni2MnGa is researched by the projected augmented wave method based on the first-principles of density functional theory. The results show that it generates distortion from regular octahedron structure to elongated octahedron structure with martensitic transformation in Ni2MnGa. This distortion is derived from a strong band Jahn？CTeller effect involving non-uniform distribution of electrons of orbit of ionic Ni, its mechanism is: the ligands pointing to x and y directions move inward and the ligands pointing to z directions move outward due to unpaired electrons transfer to orbit from orbit, this can lead to the eliminate degeneracy of energy level derived from the rising of energy levels of and , and the lowering of energy levels of , and , and thus the system energy decreases, the system changes to the stabilized martensitic phase.