Ti及氢化物几何与电子结构的密度泛函理论研究

Density Functional Theory Study on Geometric and Electronic Structure of Ti and Its Hydride

摘要:

采用基于密度泛函理论（DFT）的总体能量平面波超软赝势方法，结合广义梯度近似（GGA），对hcp结构的Ti及Ti-H体系超原胞进行第一性原理计算，获得该体系结构的晶格常数、总体能量、能带结构、态密度以及Mulliken布居数等参数。结果表明：Ti晶胞中引入H原子后，晶体杂质形成能降低，晶胞体积发生膨胀，且随氢含量增加，晶胞晶格畸变程度越大，体积增加越明显；从能带结构、电子态密度分布及布居电荷变化可知，加入H后晶胞中储存H的八面体原子间大部分Ti-Ti键增强，费米面向低能方向移动，合金活性得到改善，发生转移的电子主要以TiP轨道电子为主。

Abstract:

First-principle calculation was carried out on the Ti of hcp structure and Ti-H system supercells by a total-energy plane-wave ultrasoft pseudopotential method based on density functional theory (DFT), which combined generalized gradient approximation(GGA). Lattice parameters, total energy, energy band structure, density of states (DOS) and Mulliken population of the system were obtained. The calculated results reveal that after H atom introduction into the crystal cell of Ti8, Ti16 and Ti32, the formation energy of crystal impurity was decreased and the volume of crystal cell was swollen; the distortion would become serious and the volume would be increased obviously along with increase of the hydrogen concentration in the crystal cell. The intensity of the great mass of Ti-Ti bonds were enhanced in the octahedron storing H atom of crystal cell. The Femi energy level moved to the direction of low energy of DOS. The activity of Ti alloys was improved, and the transferred electrons were mainly those on the P orbit of Ti.