Details of a theoretical model for electronic structure of the diamond vacancies

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• 作者：Heidari Saani ; M. ; Vesaghi ; M.A. ; Esfarjani ; K. ; Shafiekhani ; A.
• 关键词：Diamond ; Vacancies ; Generalized Hubbard model ; Electronic states
• 刊名：Diamond and Related Materials
• 出版年：2004
• 出版时间：November - December, 2004
• 年：2004
• 卷：13
• 期：11-12
• 页码：2125-2130
• 全文大小：180 K

文摘

A new model to calculate electronic states of the diamond vacancies has been developed using many body techniques. This model is based on physical assumptions of previous molecular models but does not use configuration interaction. Present model allows an accurate and unified treatment of electronic levels and related eigen functions for diamond vacancies, in addition to transition energies of the first dipole-allowed transitions in the neutral (V⁰) and negatively charged (V⁻) vacancies, GR1 and ND1 band. For the first time, we calculated their optical transition intensities. For obtaining these results, we solved a generalized form of the Hubbard Hamiltonian, which consists of all electron–electron interaction terms on atomic orbital basis. Spatial symmetry of the defect, T_d symmetry, is included in the form of the Hamiltonian, and the eigen states have automatically the correct spin and symmetry properties. We discuss the possibility of the reduction of the wide gap between theoretical and semiempirical wisdom by including deformation of the dangling orbital or delocalization of the vacancy electrons to the next nearest neighbor (NNN) atoms of the vacancies. Our prediction for low lying the ³T₁ level of the neutral vacancy in diamond is consistent with experimental expectations. We report the variation of the ground and excited states of the GR1 and ND1 lines with hopping parameter t and also the electronic configurations of these states.