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changes to VASP CSC calculations in doc.

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This commit is contained in:
Alexander Hampel 2020-01-03 11:01:08 +01:00
parent 13252201e3
commit cf6789fd97
2 changed files with 10 additions and 4 deletions
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2
doc/guide/conv_vasp.rst
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@ -394,8 +394,6 @@ with:
::
WRITE(99,'(4I6,F12.7," # of spin, # of k-points, # of bands, # of proj, Efermi" )') W%WDES%NCDIJ,NK,NB,NF,EFERMI
Please make sure that mixing in VASP is turned of IMIX=0 for CSC calculations. Otherwise VASP mixes the charge density, which in the worst case removes the effect of CSC completely.
Another critical point for CSC calculations is the function call of
`LPRJ_LDApU` in VASP. This function is not needed, and was left there for debug
purposes, but is called every iteration. Removing the call to this function in `electron.F` in line 644 speeds up the calculation significantly in the `ICHARG=5` mode. Moreover, this prevents VASP from generating the `GAMMA` file, which should ideally only be done by the DMFT code after a successful DMFT step, and then be read by VASP.

12
doc/guide/dftdmft_selfcons.rst
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@ -168,9 +168,17 @@ VASP has a special INCAR `ICHARG=5` mode, that has to be switched on to make VAS
ICHARG = 5
NELM = 1000
NELMIN = 1000
IMIX=0
Here, the flag `IMIX=0` ensures that VASP does not mix the new charge density with previous iterations. Technically, VASP runs with `ICHARG=5` in a NSCF mode. Therefore, one needs to make sure to start with a converged `WAVECAR` file! To understand the difference please make sure to read `ISTART flag VASP wiki <https://www.vasp.at/wiki/index.php/ISTART>`_. Furthermore, the flags `NELM` and `NELMIN` ensure that VASP does not terminate after the default number of iterations of 60.
Technically, VASP runs with `ICHARG=5` in a SCF mode, and adding the DMFT
changes to the DFT density in each step, so that the full DFT+DMFT charge
density is constructed in every step. This is only done in VASP because only the
changes to the DFT density are read by VASP not the full DFT+DMFT density.
Moreover, one should always start with a converged `WAVECAR` file, or make sure,
that the KS states are well converged before the first projectors are created!
To understand the difference please make sure to read `ISTART flag VASP wiki
<https://www.vasp.at/wiki/index.php/ISTART>`_. Furthermore, the flags `NELM` and
`NELMIN` ensure that VASP does not terminate after the default number of
iterations of 60.
Other DFT codes
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