I recently started a project to investigate point defects in GaN. I have been unable to reproduce the hyperfine parameters from previous calculations [PRL 109, 206402 (2012)]. Specifically, my spin density values are much more delocalized especially when taking core polarization effects into account. Attached are the calculations and a summary doc. please advise.
HF Parameters for defects in GaN
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blair_tuttle
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HF Parameters for defects in GaN
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blair_tuttle
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Re: HF Parameters for defects in GaN
For more context, the author of the previous HF calculations [PRL 109, 206402 (2012)] mentioned that a relativistic expression for the HF parameters needs to be used for scalar relativistic pseudopotentials. I am not sure how this effects PAW results.
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alexey.tal
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Re: HF Parameters for defects in GaN
Dear blair_tuttle,
Thank you for your question.
Indeed, I see that the values reported in [PRL 109, 206402 (2012)] differ from the ones you find with VASP. However, I found some traces of HSE calculation in you INCAR, i.e., HFSCREEN = 0.2. But on the other hand you use LHFCALC=.FALSE.. After looking at the paper I can't tell if the results you use as a reference are produced with PBE or HSE. As far as I know, the choice of xc functional can largely affect the hyperfine tensor calculation (see Szász et al., Phys. Rev. B, 075202 (2013)). That would also explain why the spin density is much more delocalized in your case as the PBE tends to delocalized the charge density compared to hybrid functionals. Are you sure that it is the PBE values you are using as a reference and not HSE?
Kind regards,
Alexey