Optical properties

[krahil]

Hello,
I tried to analyse optical spectrum using both exchange correlation 'GGA' & 'MGGA'.
Both results are totally different and GGA is converging fast as compared to MGGA.
Which of the results are reliable - 'GGA' or 'MGGA'?

[Daniele Stradi]

For semiconductors, a correct description of the band gap is important to evaluate the optical properties. Therefore, MGGA should be preferred, since this exchange-correlation functional gives much better band gaps for semiconductors, compared to GGA.
Check more in the following tutorial:
https://docs.quantumwise.com/tutorials/optical/optical.html