用第一性原理研究Heusler合金Ni_2MnAl的电子结构、压力响应及柔和四方变形

Electronic Structure,Response to Pressure and Soft Tetragonal Distortions for Heusler Alloy Ni_2MnAl Studied via First-Principles

运用基于密度泛函理论第一性原理的投影扩充波函数(PAW)方法,计算了化学计量Ni2MnAl的晶体结构、磁性、电子结构、压力响应以及柔和四方变形.结果表明:在Ni2MnAl的总磁矩中,Mn原子对总磁矩的贡献最大;在Ni2MnAl的总态密度中,低能部分主要由Al-s的投影态密度决定,高能部分主要由Ni-d,Mn-d和Al-p的投影态密度决定;Ni和Mn原子间存在较强的键合,Al的p态和Mn的d态存在与自旋相关的杂化;在Ni2MnAl的四方变形中,0.95<c/a<1.10内存在一个变化平缓的能量面.

Crystal structure,magnetism,electronic structure,response to pressure and soft tetragonal distortions of stoichiometric composition Ni2MnAl were calculated by means of first-principles method the projected augmented wave （PAW） function based on the density functional theory. The calculations show the contribution of the spin magnetic moments of Mn atom to the total moments is the largest for Ni2MnAl. The low energy part of the total DOS is decided by Al-s-projected DOS,however,the high energy part of the total DOS is decided by Ni-d-projected DOS and Mn-d-projected DOS and Al-p-projected DOS for Ni2MnAl. The strong bonding exists between the Ni atom and the Mn atom,the spin correlation hybridization exists between the p state of Al and the d state of Mn. The entire energy surface for 0.95c/a1.10 is remarkably flat in tetragonal distortions for Ni2MnAl.