Wave function in real space can't reproduce charge density from CHGCAR

[QianM-19]

Hi Qijing,

Thanks for sharing the code with us. My team is recently working on extracting wave functions in real space using your code vaspwfc. And we check the 2-atom GaAs in rho cell. Since the |real part|^2+|imginary part|^2 of the wave function is the charge density, we compared the charge density calculated by the wave function and PARCHG generated by VASP itself for GaAs conduction band minimum. Here's the result we get.

charge density calculated by |real part|^2+|imginary part|^2

charge density by PARCHG at Gamma point pf conduction band minimum.

Do you know why there's a difference? Also, I can provide sample files if you would like.

Thank you very much again!

Qian

[QijingZheng]

Hi

Yes, there is a difference between VASP PARCHG and the charge density calculated by my script.

The reason is that may code only deals with WAVECAR file, which contains only the information of the pseudo-wavefunction. Therefore, the charge density obtained by my code is the pseudo-charge density, which does not include the charge density within the PAW augmentation sphere. On the other hand, if you look into the source code of VASP, e.g. line 1193, pardens.F vasp.5.4.4, you could see that VASP call the DEPLE subroutine, which is defined in line 2748 of us.F and adds the augmentation-density to the pseudo charge density.

Best Qijing

[QianM-19]

Hi Qijing,

That makes much more sense, thank you very much for your reply!

Thanks! Qian

On Thu, Apr 30, 2020 at 3:13 AM 郑奇靖 notifications@github.com wrote:

Hi

Yes, there is a difference between VASP PARCHG and the charge density calculated by my script.

The reason is that may code only deals with WAVECAR file, which contains only the information of the pseudo-wavefunction. Therefore, the charge density obtained by my code is the pseudo-charge density, which does not include the charge density within the PAW augmentation sphere. On the other hand, if you look into the source code of VASP, e.g. line 1193, pardens.F vasp.5.4.4, you could see that VASP call the DEPLE subroutine, which is defined in line 2748 of us.F and adds the augmentation-density to the pseudo charge density.

Best Qijing

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-- Qian Meng Graduate Research Assistant Laboratory for Advanced Semiconductor Epitaxy (LASE) Department of Electrical and Computer Engineering The University of Texas at Austin E-mail: qmeng19@utexas.edu Mobile: 512-203-9157