Role of screening in the density functional applied to transition-metal defects in semiconductors
PHYSICAL REVIEW B 87 , 205201 (2013)
In our work we investigated the mixed system of correlated and uncorrelated states as transitional metal impurities in semiconductor host which built up from built up from d-orbital like defect states in the bath of sp3 hybridized delocalized orbitals. Our results clearly show that the widespread HSE06 hybrid functional cannot describe such complex system correctly. The source of the discrepancies is the homogeneous screening of the bare Coulomb interaction. By introducing the point defect to the host semiconductor, this approximation becomes invalid and causes significant errors for transition metal impurities. We developed a scheme, HSE06+Vw, which can correct the HSE06 functional by introducing an additional screening potential to break the homogeneous screening. The corrected charge transition levels and optical excitation energies are remarkably close to the results of experimental measurements and many-body perturbation theory calculations.
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Last updated: 06/24/13