Realistic inversion of diffraction data for an amorphous solid: The case of amorphous silicon

Article

关键词: REVERSE MONTE-CARLO;    DISORDERED-SYSTEMS;    COMPUTER-SIMULATION;    INFORMATION;    REFINEMENT;    GENERATION;    SPECTRUM;    CARBON;    STATES;    VOIDS;   

DOI  :  10.1103/PhysRevB.94.235208

来源: SCIE

【 摘 要 】

We apply a method called force-enhanced atomic refinement (FEAR) to create a computer model of amorphous silicon (a-Si) based upon the highly precise x-ray diffraction experiments of Laaziri et al. [Phys. Rev. Lett. 82, 3460 (1999)]. The logic underlying our calculation is to estimate the structure of a real sample a- Si using experimental data and chemical information included in a nonbiased way, starting from random coordinates. The model is in close agreement with experiment and also sits at a suitable energy minimum according to density-functional calculations. In agreement with experiments, we find a small concentration of coordination defects that we discuss, including their electronic consequences. The gap states in the FEAR model are delocalized compared to a continuous random network model. The method is more efficient and accurate, in the sense of fitting the diffraction data, than conventional melt-quench methods. We compute the vibrational density of states and the specific heat, and we find that both compare favorably to experiments.

【 授权许可】

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