Ca，Pd，Sn，La对MgH2电子结构的影响

Ca, Pd, Sn and La Effects on the Electronic Structure of MgH2

摘要:

采用基于第一原理的离散变分方法(DVM),研究了Ca,Pd,Sn,La等原子替代镁氢化物MgH2原子团簇中心Mg原子对镁氢化物电子结构及其成键特性的影响.通过分析晶体轨道重叠集居数(COOP),键序(BO)和键差分电荷密度等计算结果表明Ca,Pd,Sn,La等原子对关系到Mg(M)H2结构稳定性的Mg-H键具有明显影响;它们最近邻镁原子周围的电荷密度重新分布并具有明显的各向异性,当M是Ca,Pd,La时,其最近邻Mg和H之间键序变化不大,稍有增加,当M是Sn时,则大幅减弱,其逐增顺序为Sn＜La＜Pd＜Ca;而且,对其它位置Mg与氢之间相互作用也有一定程度的影响.

Abstract:

The effect of Ca, Pd, Sn and La atoms substitution for the central Mg atom of magnesium hydride Mg(M)H2 atom cluster on electronic structure and bonding characterization have been studied by using the discrete variational method (DVM) based on the first principles. The crystal orbital overlap population (COOP), the bond order (BO) and the bonding charge densities were analyzed by calculation. It showed that the substitution atoms Ca, Pd, Sn and La had an obvious effect on the chemical bond Mg-H which corresponds to the stable of Mg(M)H2 structure. The charge densities around their nearest neighbor Mg are redistributed and obviously anisotropic. When M is Ca, Pd or La, BO between the nearest neighbor Mg and H is almost same and increased slightly; when M is Sn, it is greatly decreased. The increased order is Sn < La < Pd < Ca. And the interactions between the other Mg atoms and hydrogen are also affected to some degree.