Numerical study of the electronic structure of amorphous silica

Article

关键词: MOLECULAR-DYNAMICS;    ALPHA-QUARTZ;    COMPUTER-SIMULATION;    VITREOUS-SILICA;    PRESSURE;    LIQUID;    SIO2;    CRYSTALLINE;    ALLOYS;    POLYMORPHS;   

DOI  :  10.1103/PhysRevB.56.9469

来源: SCIE

【 摘 要 】

We present a computational study of the electronic properties of amorphous SiO2. The ionic configurations used are the ones generated by earlier molecular-dynamics simulations in, which the system was cooled with different cooling rates from the liquid to a glass state, thus giving access to glasslike configurations with different degrees of disorder [Phys. Rev. B 54, 15808 (1996)]. The electronic structure is described by a tight-binding Hamiltonian. We study the influence of the degree of disorder on the density of states, the localization properties, the optical absorption, the nature of defects within the mobility gap, and on the fluctuations of the Madelung potential, where the disorder manifests itself most prominently. The experimentally observed mismatch between a photoconductivity threshold of 9 eV and the onset of the optical absorption around 7 eV is interpreted by the picture of eigenstates localized by potential-energy fluctuations in a mobility gap of similar to 9 eV and a density of states that exhibits valence-and conduction-band tails which are, even in the absence of defects, deeply located within the former band gap.

【 授权许可】

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