六钛酸钾(K_2Ti_6O_(13))晶须几何构型、能量及电子结构的第一性原理计算

First-principles Calculation of the Geometric Configuration,Energies and Electronic Structures of Potassium Hexatitanate Whisker

本文采用基于密度泛函理论的第一性原理计算方法,对具有单斜结构六钛酸钾(K2Ti6O13)晶体的几何构型、能量及电子结构进行系统研究。计算所得K2Ti6O13晶体的晶格常数、原子位置等晶胞参数均与实验值吻合,且形成热与结合能的计算结果显示该晶体具有较高的相结构稳定性;进一步的电子结构分析表明,K2Ti6O13晶体呈现具有间接带隙的半导体性质,在K2Ti6O13内部,Ti-O间成键作用明显强于K-O,而K-Ti间却未明显成键,且Ti(d)与O(p)轨道电子间较强的共价键相互作用直接决定了K2Ti6O13晶体的相结构稳定性。

The geometric configuration, energies and electronic structures of monoclinic potassium hexatitanate （K2Ti6O13） were investigated systematically by first-principle calculation method based on density functional theory. It is found that the crystal primitive cell parameters including lattice constantsand atomic positions calculated here are in good agreement with the experimental data. The calculation results of formation heat and cohesive energy reveal that K2Ti6O13exhibits high structural stability.Further analysis of the electronic structures shows that the potassium hexatitanate is wide-band semiconductor. Within K2Ti6O13 crystal, the Ti-O bonding interactions are stronger than that of K-O, while no apparent K-Ti bonding interactions can be observed. The structural stability of K2Ti6O13 is closely depended on covalent bond interactions between Ti （d） and O（p） orbits.