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运用基于密度泛函理论的第一性原理,对Hg2CuTi型Mn2NiGe的四方变形、晶体结构、磁性、电子结构、压力响应等进行了计算.计算结果表明:1)在由立方结构至四方结构的转变中,在c/a约为1.34处存在一个稳定的马氏体相;2)在奥氏体态和马氏体态下,Mn原子均是Mn2NiGe总磁矩的主要贡献者,但Mn(A),Mn(B)原子磁矩的值不等且呈反平行耦合,因而Mn2NiGe合金均表现为亚铁磁结构;3)在奥氏体态和马氏体态下,Mn(A),Mn(B)原子之间的亚铁磁耦合是由它们之间弱的d-d直接交换作用来维持.根据以上的计算结果,预测Mn2NiGe具有磁性形状记忆效应.
The tetragonal deformation, crystal structure, magnetic property, electronic structure and pressure response of Hg2CuTi Mn2NiGe were calculated by using the first principle based on density functional theory. The calculation results show that: 1) In the transition from cubic structure to tetragonal structure , A stable martensite phase exists at c / a about 1.34; 2) Mn atoms are the major contributors to the total magnetic moment of Mn2NiGe in both austenite and martensite, but Mn (A) , Mn (B) atoms have different magnetic moments and are antiparallel-coupled. Therefore, the Mn2NiGe alloys all exhibit ferrimagnetism. (3) In the austenite and martensite states, ) Ferrimagnetic coupling between atoms is maintained by the direct exchange of weak dd between them.According to the above calculation results, it is predicted that Mn2NiGe has a magnetic shape memory effect.