RENi_5及其氢化物电子结构与吸氢性能的相关性研究

STUDY ON THE CORRELATION BETWEEN ELECTRONIC STRUCTURES OF RENi_5 AND THEIR HYDRIDES AND HYDROGEN ABSORPTION PROPERTIES

利用电荷自洽离散变分 Ｘ_α（ＳＣＣ－ＤＶ－Ｘ_α）方法计算了 ＲＥＮｉ_５（ＲＥ＝Ｌａ， Ｃｅ； Ｐｒ， Ｎｄ）及其氢化物的电子结构，分析了电子结构对吸氢性能的影响，结果表明： ＲＥＮｉ_５氢化物的稳定性与氢原子的电荷转移密切相关，进入 Ｈ １ｓ轨道的电荷增大，将会降低其稳定性； Ｎｉ ３ｄ轨道不与氢原子作用，而与 ＲＥ ４ｆ轨道有较强的成键作用，但这种作用在吸氢后被明显减弱；ＲＥＮｉ_５平台氢压随着相应氢化物Ｆｅｒｍｉ能级的提高而降低．

The electronic structures of RENi_5 (RE=La, Ce, Pr, Nd) and their hydrides were investigated by the SCC-DV-Xa (self-consistent-charge discrete variational Xa ) method. The results show that the stabilities of RENi_5 hydrides are related to charge transferred to hydrogen atom, and decrease with increase of the transferred charge. There is a strong orbital interaction between 3d orbit in Ni atom and 4f orbit in RE atom, which is weaken when hydride is formed. The equilibrium plateau pressure of RENi_5 rises with lowering of Fermi energy of hydride.