中文摘要：

采用基于密度泛函理论（DFF）的平面波超软赝势法，用广义梯度近似（GGA）PBE交换相关泛函，对高压相变产生五种不同SnO2晶体结构的电子结构和力学性质进行了第一性原理计算．计算结果表明，Pnam型SnO2的形成相对困难，体模量较大，Pbca和Pnam型SnO2的维氏硬度值相差不明显．不同晶体结构的带隙存在差异，导带区域电子分布和弥散程度大于价带区域，局域性差．五种SnO2晶体结构的价带部分约在一10—0eV和-20--15ev处，主要贡献来自于O2p、2s轨道．光学性质计算表明，Pnam结构对紫外波段光的吸收最明显，同时给出电子轨道跃迁规律．

英文摘要：

Mechanical and electronic properties of different SnO2 crystal structures were studied by density functional theory. For the exchange-correction energy we employed the generalized gradient approximation （GGA） in the PBE （Perdew, Burke and Ernzerhof） form. The lattice constants, bulk modulus and Young＇ s modulus of the studied isomers are obtained. By comparing the space groups of Pbca and Pnam in SnO2 the Vickers hardness of the two crystal structures was found to be consistent. There was a difference in the band gap between the SnO2 isomers. Energies of valence bands varied from -10 to 0 eV and -20 to -15 eV for all SnO2 crystals. These valence bands resulted from the O 2p and 2s orbitals. Optical properties of these SnO2 isomers were also calculated. The absorption spectrum of Pnam showed a strong peak in the ultraviolet range. Rules for electron transitions were determined for the different space groups of SnO2.