2018-08-07 11:35:29 +02:00
|
|
|
.. _convVASP:
|
|
|
|
|
|
|
|
|
|
|
|
Interface with VASP
|
|
|
|
===================
|
|
|
|
|
|
|
|
.. warning::
|
|
|
|
The VASP interface is in the alpha-version and the VASP part of it is not
|
|
|
|
yet publicly released. The documentation may, thus, be subject to changes
|
|
|
|
before the final release.
|
|
|
|
|
|
|
|
*Limitations of the alpha-version:*
|
|
|
|
|
|
|
|
* The interface works correctly only if the k-point symmetries
|
|
|
|
are turned off during the VASP run (ISYM=-1).
|
|
|
|
|
|
|
|
* Generation of projectors for k-point lines (option `Lines` in KPOINTS)
|
|
|
|
needed for Bloch spectral function calculations is not possible at the moment.
|
|
|
|
|
|
|
|
* The interface currently supports only collinear-magnetism calculation
|
|
|
|
(this implis no spin-orbit coupling) and
|
|
|
|
spin-polarized projectors have not been tested.
|
|
|
|
|
|
|
|
A detailed description of the VASP converter tool PLOVasp can be found
|
|
|
|
in :ref:`plovasp`. Here, a quick-start guide is presented.
|
|
|
|
|
|
|
|
The VASP interface relies on new options introduced since version
|
|
|
|
5.4.x. In particular, a new INCAR-option `LOCPROJ`
|
|
|
|
and new `LORBIT` modes 13 and 14 have been added.
|
|
|
|
|
|
|
|
Option `LOCPROJ` selects a set of localized projectors that will
|
|
|
|
be written to file `LOCPROJ` after a successful VASP run.
|
|
|
|
A projector set is specified by site indices,
|
|
|
|
labels of the target local states, and projector type:
|
|
|
|
|
|
|
|
| `LOCPROJ = <sites> : <shells> : <projector type>`
|
|
|
|
|
|
|
|
where `<sites>` represents a list of site indices separated by spaces,
|
|
|
|
with the indices corresponding to the site position in the POSCAR file;
|
|
|
|
`<shells>` specifies local states (see below);
|
|
|
|
`<projector type>` chooses a particular type of the local basis function.
|
2018-12-12 14:16:54 +01:00
|
|
|
The recommended projector type is `Pr 2`. The formalism for this type
|
|
|
|
of projectors is presented in
|
|
|
|
`M. Schüler et al. 2018 J. Phys.: Condens. Matter 30 475901 <https://doi.org/10.1088/1361-648X/aae80a>`_.
|
2018-08-07 11:35:29 +02:00
|
|
|
|
|
|
|
The allowed labels of the local states defined in terms of cubic
|
|
|
|
harmonics are:
|
|
|
|
|
|
|
|
* Entire shells: `s`, `p`, `d`, `f`
|
|
|
|
|
|
|
|
* `p`-states: `py`, `pz`, `px`
|
|
|
|
|
|
|
|
* `d`-states: `dxy`, `dyz`, `dz2`, `dxz`, `dx2-y2`
|
|
|
|
|
|
|
|
* `f`-states: `fy(3x2-y2)`, `fxyz`, `fyz2`, `fz3`,
|
|
|
|
`fxz2`, `fz(x2-y2)`, `fx(x2-3y2)`.
|
|
|
|
|
|
|
|
For projector type `Pr 2`, one should also set `LORBIT = 14` in INCAR
|
|
|
|
and provide parameters `EMIN`, `EMAX` which, in this case, define an
|
|
|
|
energy range (window) corresponding to the valence states. Note that as in the case
|
|
|
|
of DOS calculation the position of the valence states depends on the
|
|
|
|
Fermi level.
|
|
|
|
|
|
|
|
For example, in case of SrVO3 one may first want to perform a self-consistent
|
|
|
|
calculation, then set `ICHARGE = 1` and add the following additional
|
|
|
|
lines into INCAR (provided that V is the second ion in POSCAR):
|
|
|
|
|
|
|
|
| `EMIN = 3.0`
|
|
|
|
| `EMAX = 8.0`
|
|
|
|
| `LORBIT = 14`
|
|
|
|
| `LOCPROJ = 2 : d : Pr 2`
|
|
|
|
|
|
|
|
The energy range does not have to be precise. Important is that it has a large
|
|
|
|
overlap with valence bands and no overlap with semi-core or high unoccupied states.
|
|
|
|
|
|
|
|
Conversion for the DMFT self-consistency cycle
|
|
|
|
----------------------------------------------
|
|
|
|
|
|
|
|
The projectors generated by VASP require certain post-processing before
|
|
|
|
they can be used for DMFT calculations. The most important step is to normalize
|
|
|
|
them within an energy window that selects band states relevant for the impurity
|
|
|
|
problem. Note that this energy window is different from the one described above
|
|
|
|
and it must be chosen independently of the energy
|
|
|
|
range given by `EMIN, EMAX` in INCAR.
|
|
|
|
|
|
|
|
Post-processing of `LOCPROJ` data is generally done as follows:
|
|
|
|
|
|
|
|
#. Prepare an input file `<name>.cfg` (e.g., `plo.cfg`) that describes the definition
|
|
|
|
of your impurity problem (more details below).
|
|
|
|
|
|
|
|
#. Extract the value of the Fermi level from OUTCAR and paste at the end of
|
|
|
|
the first line of LOCPROJ.
|
|
|
|
|
|
|
|
#. Run :program:`plovasp` with the input file as an argument, e.g.:
|
|
|
|
|
|
|
|
| `plovasp plo.cfg`
|
|
|
|
|
|
|
|
This requires that the TRIQS paths are set correctly (see Installation
|
|
|
|
of TRIQS).
|
|
|
|
|
|
|
|
If everything goes right one gets files `<name>.ctrl` and `<name>.pg1`.
|
|
|
|
These files are needed for the converter that will be invoked in your
|
|
|
|
DMFT script.
|
|
|
|
|
|
|
|
The format of input file `<name>.cfg` is described in details in
|
|
|
|
:ref:`plovasp`. Here we just give a simple example for the case
|
|
|
|
of SrVO3:
|
|
|
|
|
|
|
|
.. literalinclude:: images_scripts/srvo3.cfg
|
|
|
|
|
|
|
|
A projector shell is defined by a section `[Shell 1]` where the number
|
|
|
|
can be arbitrary and used only for user convenience. Several
|
|
|
|
parameters are required
|
|
|
|
|
|
|
|
- **IONS**: list of site indices which must be a subset of indices
|
|
|
|
given earlier in `LOCPROJ`.
|
|
|
|
- **LSHELL**: :math:`l`-quantum number of the projector shell; the corresponding
|
|
|
|
orbitals must be present in `LOCPROJ`.
|
|
|
|
- **EWINDOW**: energy window in which the projectors are normalized;
|
|
|
|
note that the energies are defined with respect to the Fermi level.
|
|
|
|
|
|
|
|
Option **TRANSFORM** is optional but here it is specified to extract
|
|
|
|
only three :math:`t_{2g}` orbitals out of five `d` orbitals given by
|
|
|
|
:math:`l = 2`.
|
|
|
|
|
|
|
|
The conversion to a h5-file is performed in the same way as for Wien2TRIQS::
|
|
|
|
|
|
|
|
from triqs_dft_tools.converters.vasp_converter import *
|
|
|
|
Converter = VaspConverter(filename = filename)
|
|
|
|
Converter.convert_dft_input()
|
|
|
|
|
|
|
|
As usual, the resulting h5-file can then be used with the SumkDFT class.
|
|
|
|
|
|
|
|
Note that the automatic detection of the correct block structure might
|
|
|
|
fail for VASP inputs.
|
|
|
|
This can be circumvented by setting a bigger value of the threshold in
|
|
|
|
:class:`SumkDFT <dft.sumk_dft.SumkDFT>`, e.g.::
|
|
|
|
|
|
|
|
SK.analyse_block_structure(threshold = 1e-4)
|
|
|
|
|
|
|
|
However, do this only after a careful study of the density matrix and
|
|
|
|
the projected DOS in the localized basis.
|
|
|
|
|