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中文摘要：
应用基于密度泛函理论的赝势-平面波方法研究了Nb2H的电子结构和H原子占据点之间的关系,计算结果表明：由4个Nb近邻构成的四面体中心点（T点）为H的稳定俘获点，而由6个Nb近邻构成的八面体中心点（0点）则为相互作用势的极大值点，是不稳定点,相邻T点间存在低能量通道，具有鞍点（S点）结构,在T点及近邻低能通道上，H的1s能级展宽较弱，Nb的4d，5s带部分向下延展，与H带杂化后形成孤立带,当H由T向O移动时，孤立的杂化带向金属价带靠近，带隙逐渐消失,H处于完整宿主晶格中的T点时，布里渊区Г点处的光学声子结构色散较强，而在远离Г点处的色散很弱,H在T点邻域及T-T通道上的电子结构稳定性和声子的色散关系表明，H倾向于以稳定负离子形式存在。
英文摘要：
The total energies and electronic structures of differently configured Nb2 H are calculated using pseudopotential plane wave method based on density functional theory and generalized gradient approximation. The results show that hydrogen atom favors tetrahedral （T） sites （T-wells） rather than octahedral （O） ones. There exist lower energy paths along adjacent T-T sites and saddle structures at the midpoint of them. When H is at T-site or along the T-T path, its ls level is less broadened and the 4d, 5s bands of Nb extend downward from the metallic band area, forming an ionic band （sharp peak） separated by a gap of about 1 eV from the metallic valence bands, showing that the hydrogen atom captures one valence electron to form an anion. This low- lying ionic band loses its T-site hybridization features when H moves from T to O site, where the ls band of H is widely broadened, extending into the metallic valence bands. The band structure changes only slightly when the hydrogen atom moves from one T site to a neighbor one along the lower energy path, keeping the T-configuration features. The calculated phonon spectra of H are dispersive only near special q-points for the system with H at a T site, showing that the hydrogen atom is probably vibraing locally and weakly interacts with other hydrogen atoms. The behavior of H at a trapping site plays an important role in bonding of the surrounding Nb atoms.
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