TiB₂电子结构、光学和晶格动力学性质的第一性原理计算

First Principles Calculation of the Electronic Structure, Optical and Lattice Kinetic Properties of TiB₂

摘要: 利用基于密度泛函理论的第一性原理计算了TiB₂的电子结构、光学和晶格动力学性质。计算表明TiB₂具有金属特征，导带主要由B原子的2p轨道反键态和Ti原子的3d电子构成。B原子的σ键由2s和2p杂化轨道形成，pz轨道单独形成一个连续的π键，这些态间的跃迁在吸收光谱中体现。电子云轨道分布表明TiB₂的Ti原子的3d向B原子的2p轨道转移，和MgB₂的电荷转移相似。晶格动力学计算表明TiB₂中LA (LO)和TA (TO)间的分裂显著，频率较高的部分都来自于六方平面B原子的振动。对声子谱中Γ点处9条色散分别对应的频率进行了标定，最后预测TiB₂超导温度接近0 K。

Abstract: The electronic structure, optical and lattice dynamics properties of TiB₂ are calculated by using the first principles of density functional theory. The calculation results show that the TiB₂ has metallic characteristics, and the conduction band is mainly composed of the 2p orbital antibonding state of B atom and the 3d electron of Ti atom. The σ bonds of B atoms are formed from 2s and 2p hybridized orbitals, and the pz orbitals form a single continuous π bond. The transitions between these states are reflected in the absorption spectrum. The electron cloud orbital distribution indicates that the 3d orbital of Ti atom transfer to the 2p orbital of B atom in TiB2, is similar to the charge transfer of MgB₂. Lattice dynamics calculations show that the splitting between LA (LO) and TA (TO) in TiB₂ is significant, and the higher part of the frequency comes from the vibration of the B atom in the hexagonal plane. All of the nine eigen values at Γ point are summarized and labeled according to their frequency. The prediction of TiB₂ superconducting temperature should be 0 K.