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QuantumATK => General Questions and Answers => Topic started by: abhishek77492652 on September 27, 2017, 19:37

Title: Underestimation of bandgap
Post by: abhishek77492652 on September 27, 2017, 19:37

Why DFT-GGA and DFT-LDA underestimate the bandgap  of  non-metals ?

Title: Re: Underestimation of bandgap
Post by: Daniele Stradi on September 28, 2017, 09:16

Because of the so-called self-interaction error due to the use of approximate exchange-correlation functionals. See e.g.:

J. P. Perdew and Alex Zunger
Self-interaction correction to density-functional approximations for many-electron systems
Phys. Rev. B 23, 5048
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.23.5048