Communication: Hole localization in Al-doped quartz SiO2 within ab initio hybrid-functional DFT

摘要

We investigate the long-standing problem of hole localization at the Al impurity in quartz SiO2, using\uda relatively recent DFT hybrid-functional method in which the exchange fraction is obtained ab initio,\udbased on an analogy with the static many-body COHSEX approximation to the electron self-energy.\udAs the amount of the admixed exact exchange in hybrid functionals has been shown to be determinant\udfor properly capturing the hole localization, this problem constitutes a prototypical benchmark for\udthe accuracy of the method, allowing one to assess to what extent self-interaction effects are avoided.\udWe obtain good results in terms of description of the charge localization and structural distortion\udaround the Al center, improving with respect to the more popular B3LYP hybrid-functional approach.\udWe also discuss the accuracy of computed hyperfine parameters, by comparison with previous\udcalculations based on other self-interaction-free methods, as well as experimental values. We discuss\udand rationalize the limitations of our approach in computing defect-related excitation energies in lowdielectric-\udconstant insulators. C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4931405]