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QuantumATK => General Questions and Answers => Topic started by: mastaAce on November 2, 2012, 18:17

Title: How to calculate correct bandstructure of GaSb?
Post by: mastaAce on November 2, 2012, 18:17

Hi everyone!

I must ask you how to obtain correct bandstructure of cystals based on Gallium e.g. on GaSb compound. I've tried a few methods, but allways my energy gap is about 0 eV. Could somebody try do it on his own, and share the results with me? Probably I'm missing something so I need your advice. Thanks in advance!

Title: Re: How to calculate correct bandstructure of GaSb?
Post by: zh on November 5, 2012, 02:23

This may be the typical underestimation of band gap by LDA or GGA.  The experimental band gap of GaSb is 0.726 eV (http://www.ioffe.rssi.ru/SVA/NSM/Semicond/GaSb/bandstr.html).

Because the band gap of GaSb in the LDA/GGA calculation may be a small value, you may use a tiny temperature or zero for "Electron temperature" parameter.  Such setup will lead to a behaviour of nearly or exactly fixed occupation for the electron occupation.

Title: Re: How to calculate correct bandstructure of GaSb?
Post by: Anders Blom on November 5, 2012, 14:03

Using the Slater-Koster models in ATK-SE gives very reasonable band structures. For DFT, you can try LDA+U or GGA+U to adjust the band gap, but that's a bit more work.

I also tried MGGA, interestingly that doesn't work at all.