摘要:
在密度泛函理论框架下，利用GGA + U方法，本文对二氧化钒的金属绝缘体相变及电学性质进行了详细的研究。研究发现，一旦考虑占位关联效应，不管在高温R相还是低温M1相的二氧化钒中都可以得到绝缘体态。然而在M1相中，能隙的突然打开现象与实验观测现象非常一致。另外，在金属绝缘体相变过程中，中心钒原子和其周边的6个氧配位体之间发生了一个有趣的电荷转移现象。这一现象表明二氧化钒中发生的金属绝缘体相变应该属于电荷转移型。
Abstract:
In the framework of density functional theory, the electronic structure and the metal-insulator transition (MIT) mechanism of vanadium dioxide are investigated by GGA + U method. With on- site correlation effects, insulating states can be obtained in both high temperature rutile and low temperature monoclinic structures. Suddenly opening of the energy gap in the monoclinic phase is consistent with the experimental observation. Furthermore, an interesting charge-transfer from the center V ion to the 6 O ligands has been found during the MIT process, which suggests that such a MIT should be a charge-transfer type.