Underestimation of hyperfine constant

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hongyang_ma
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Underestimation of hyperfine constant

#1 Post by hongyang_ma » Mon Mar 21, 2022 6:29 am

Hi,

I'm a newbie in using VASP. I would like to use VASP to calculate the isotropic hyperfine constant of P doped Si by using the keyword "LHYPERFINE". I successfully got the results, however, the calculated hyperfine value is much smaller than the experimental value (76 MHz vs. 117 MHz). I'm wondering what is the reason that causes this underestimation? Is this due to the psedupotential which ignore the core electron contribution? Are there any possible ways to improve the results?

The input files I used and OUTCAR are attached
Files.rar
. Please have a look. Thanks you for your help.

Best Regards,
Hongyang
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marie-therese.huebsch
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Re: Underestimation of hyperfine constant

#2 Post by marie-therese.huebsch » Wed Mar 23, 2022 8:10 am

Hi Hongyang,

Thank you for bringing up this topic. Perhaps someone else has experience with this calculation and can help.

From what I gathered, the result of LHYPERFINE is very sensitive to the PAW dataset you are using. Therefore, you may try if the GW POTCAR yields different results. A computationally more expensive route could be to make use of hybrid functionals. The advantage of hybrid functionals is that you can probably set the amount of Fock exchange just right to reproduce the experimental value. From a critical standpoint that would not be fully ab initio then, because you selected a parameter to fit the experiment. Besides these suggestions, you could also benchmark against an all-electron code like Wien2k, but I don't know if they provide the analogous output for the hyperfine constant.

Best regards,
Marie-Therese

hongyang_ma
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Re: Underestimation of hyperfine constant

#3 Post by hongyang_ma » Fri Mar 25, 2022 7:50 am

Hi Marie,

Thanks for you reply. I will give it a try.

Best,
Hongyang

marie-therese.huebsch
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Re: Underestimation of hyperfine constant

#4 Post by marie-therese.huebsch » Thu Jan 18, 2024 2:14 pm

Hi Hongyang,

May I ask what you concluded after your tests?

Marie-Therese

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