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Title: An empirical, yet practical way to predict the band gap in solids by using density functional band structure calculations
Author: Morales García, Ángel
Valero Montero, Rosendo
Illas i Riera, Francesc
Keywords: Teoria del funcional de densitat
Conductivitat elèctrica
Density functionals
Electric conductivity
Issue Date: 9-Aug-2017
Publisher: American Chemical Society
Abstract: Band structure calculations based on density functional theory (DFT) with local or gradient-corrected exchange-correlation potentials are known to severely underestimate the band gap of semiconducting and insulating materials. Alternative approaches have been proposed: from semiempirical setups, such as the so-called DFT +U, to hybrid density functionals using a fraction of nonlocal Fock exchange, to modifications of semilocal density functionals. However, the resulting methods appear to be material dependent and lack theoretical rigor. The rigorous many-body perturbation theory based on GW methods provides accurate results but at a very high computational cost. Hereby, we show that a linear correlation between the electronic band gaps obtained from standard DFT and GW approaches exists for most materials and argue that (1) this is a strong indication that the problem of predicting band gaps from standard DFT calculation arises from the assignment of a physical meaning to the Kohn-Sham energy levels rather than from intrinsic errors of the DFT methods and (2) it provides a practical way to obtain GW-like quality results from standard DFT calculations. The latter will be especially useful for systems where the unit cell involves a large number of atoms as in the case of doped or defect-containing materials for which GW calculations become unfeasible.
Note: Versió postprint del document publicat a:
It is part of: Journal of Physical Chemistry C, 2017, vol. 121, num. 34, p. 18862-18866
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ISSN: 1932-7447
Appears in Collections:Articles publicats en revistes (Ciència dels Materials i Química Física)

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