PARCHG with LSORBIT=.TRUE.

[IBRAHIM]

Dear All,

This is topic is already reported without relevant solutions. It is reported in the bug section (forum/viewtopic.php?f=3&t=17832&p=19192 ... soc#p19192), and the reply is locked.

The problem is PARCHG from LSORBIT calculations, show negative values. As mentioned, it is discussed in the forum but without relevant solutions (forum/viewtopic.php?f=4&t=16810&p=17031 ... soc#p17031). Upon LSORBIT, spin-up and spin-down electron densities are not calculated, and PARCHG does not contain relevant numbers, as explained by VASP Admin.

So, how could we get the band decomposed charge density from PARCHG with LSORBIT and without those negative values? What is the format of PARCHG in that case?

Also (generally, not only in the current issue), I got the message of "Calculating partial charge density only with a part of the kpoint set. This may change the weights of the k-points. So I hope you know, what you are doing.", when I did not specify LSEPK in INCAR (so default FALSE is used), however, in that case the weight of each k point is determined normally from the KPOINTS file. Is it OK? or the weight could be changed?

But I did not get that message with LSEPK =.TRUE., however in that case the values of the k-point weights are set to 1 automatically, irrespective to the weight in BZ. 

Best regards,
Ibrahim

[marie-therese.huebsch]

Dear Ibrahim,

For LSORBIT=T the PARCHG file is unfortunately not supported. Generally, for LSORBIT the charge density is a 2x2 tensor. It can be written in terms of the spinor representation where unit matrix and the three Pauli matrices are used as a basis. See LORBIT for details on that representation. So, PARCHG could be written in the spinor representation similar to CHGCAR in a future release, but we are not currently actively implementing this feature.

To investigate the k, band, and ion decomposed character of the Kohn-Sham orbitals, I would recommend using LORBIT=11. This writes the PROCAR file which is human readable. Additionally, if you are using py4vasp, you can easily plot the band structure with the orbital character indicated at each k point and band.

Another feature you might be interested in is computing Wannier functions. There are actually multiple options, so please check the Wiki for more information.

For the issue with the weights of the k points, I will need to check this more carefully first. Sorry.

Best regards,
Marie-Therese

[siavash_karbasizadeh]

Dear All,

In the latest post on the forum about LSORBIT=T calculations, it has been mentioned that PARCHG file is not supported. I was wondering if there has been a fix for this in the latest released version of VASP.

All the best
Siavash