Author Topic: Will the PBE underestimate the bandgap?  (Read 4119 times)

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Offline perfetti

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Will the PBE underestimate the bandgap?
« on: October 9, 2012, 20:33 »
Dear every one,
       I am reading some literature and it said PBE may underestimate the bandgap of a material and may cause wrong conlusion, would that be true? Or how much would the error would be? Thank you.

Offline kstokbro

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Re: Will the PBE underestimate the bandgap?
« Reply #1 on: October 9, 2012, 23:00 »
This is correct. PBE is developed for total energy of solids, i.e. ground state properties and not the bandgap. There is no rule how large the error in band gap is.

 However, it will give you the correct workfunction. In cases where it is the valence band which is important for the conduction, it might therefore give a good description of the electron transport. If it is the valence band which is important you can use the +U correction, MetaGGA or a fitted tight binding model.