Co掺杂镧镍合金及氢化物的第一性原理研究

First-Principles Study of Co-Doped LaNi Alloy and Its Hydrid

采用基于密度泛函理论(Density functional theory’DFT)的总体能量和平面波赝势方法,计算了LaNi5-xCox(x=0,0.5)贮氢合金及其氢化物的晶体结构、电子结构和成键特性,获得了其总体能量、能带结构、态密度以及Mulliken布居值;计算结果表明:在LaNi5合金中,Ni2c与La原子间的相互作用大于Ni3g与La原子间的相互作用,Ni2c-Ni2c和Ni3g-Ni3g原子间存在明显的共价作用。合金中引入Co原子和H原子后,Ni2c-Ni2c和Ni3g-Ni3g相互作用明显减弱。H与Ni3g之间共价作用明显大于H与Ni2c间作用,即在四面体中引入H后,晶格膨胀导致Ni2c原子向外移动,使合金a轴膨胀大于c轴膨胀。

Crystal structure,electronic structure and bonding characteristics of LaNi5-xCox（x=0,0.5） and its hydride were investigated by the density functional theory based on general gradient approximation（GGA） and the ultra-soft plane-wave pseudopotential method.The total energy,energy band structure,density of states and Mulliken population were obtained.The results show that the interaction between Ni2c and La atoms is larger than that between Ni3g and La atoms in LaNi5 alloy.There is obvious covalent interaction between Ni2c―Ni2c and Ni3g―Ni3g.However,the covalent interaction is reduced after introduction of Co and H atoms.The interaction between H and Ni3g atoms is larger than that between H and Ni2c atoms.The expansion along a axis is larger than that along c axis because the lattice expansion results in outward moving of Ni2c atoms after hydrogen atom enters the tetrahedron.