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docs (conversion): update VASP-conversion documentation
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Oleg E. Peil
Manuel
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@ -189,54 +189,98 @@ Interface with VASP
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yet publicly released. The documentation may, thus, be subject to changes
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before the final release.
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Note that this VASP interface relies on new options introduced since version
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5.4.x.
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*Limitations of the alpha-version:*
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Additionally, the interface only works correctly if the k-point symmetries
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* The interface works correctly only if the k-point symmetries
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are turned off during the VASP run (ISYM=-1).
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The output of raw (non-normalized) projectors is controlled by an INCAR option
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LOCPROJ whose complete syntax is described in the VASP documentaion.
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* Generation of projectors for k-point lines (option `Lines` in KPOINTS)
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needed for Bloch spectral function calculations is not possible at the moment.
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The definition of a projector set starts with specifying which sites
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and which local states we are going to project onto.
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This information is provided by option LOCPROJ
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* The interface currently supports only collinear-magnetism calculation
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(this implis no spin-orbit coupling) and
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spin-polarized projectors have not been tested.
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A detailed description of the VASP converter tool PLOVasp can be found
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in :ref:`plovasp`. Here, a quick-start guide is presented.
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The VASP interface relies on new options introduced since version
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5.4.x. In particular, a new INCAR-option `LOCPROJ`
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and new `LORBIT` modes 13 and 14 have been added.
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Option `LOCPROJ` selects a set of localized projectors that will
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be written to file `LOCPROJ` after a successful VASP run.
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A projector set is specified by site indices,
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labels of the target local states, and projector type:
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| `LOCPROJ = <sites> : <shells> : <projector type>`
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where `<sites>` represents a list of site indices separated by spaces,
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with the indices corresponding to the site position in the POSCAR file;
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`<shells>` specifies local states (e.g. :math:`s`, :math:`p`, :math:`d`,
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:math:`d_{x^2-y^2}`, etc.);
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`<shells>` specifies local states (see below);
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`<projector type>` chooses a particular type of the local basis function.
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The recommended projector type is `Pr 2`.
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Some projector types also require parameters `EMIN`, `EMAX` in INCAR to
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be set to define an (approximate) energy window corresponding to the
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valence states.
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The allowed labels of the local states defined in terms of cubic
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harmonics are:
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When either a self-consistent (`ICHARG < 10`) or a non-self-consistent
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(`ICHARG >= 10`) calculation is done VASP produces file `LOCPROJ` which
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will serve as the main input for the conversion routine.
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* Entire shells: `s`, `p`, `d`, `f`
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* `p`-states: `py`, `pz`, `px`
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* `d`-states: `dxy`, `dyz`, `dz2`, `dxz`, `dx2-y2`
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* `f`-states: `fy(3x2-y2)`, `fxyz`, `fyz2`, `fz3`,
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`fxz2`, `fz(x2-y2)`, `fx(x2-3y2)`.
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For projector type `Pr 2`, one should also set `LORBIT = 14` in INCAR
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and provide parameters `EMIN`, `EMAX` which, in this case, define an
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energy range (window) corresponding to the valence states. Note that as in the case
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of DOS calculation the position of the valence states depends on the
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Fermi level.
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For example, in case of SrVO3 one may first want to perform a self-consistent
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calculation, then set `ICHARGE = 1` and add the following additional
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lines into INCAR (provided that V is the second ion in POSCAR):
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| `EMIN = 3.0`
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| `EMAX = 8.0`
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| `LORBIT = 14`
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| `LOCPROJ = 2 : d : Pr 2`
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The energy range does not have to be precise. Important is that it has a large
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overlap with valence bands and no overlap with semi-core or high unoccupied states.
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Conversion for the DMFT self-consistency cycle
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""""""""""""""""""""""""""""""""""""""""""""""
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In order to use the projectors generated by VASP for defining an
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impurity problem they must be processed, i.e. normalized, possibly
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transformed, and then converted to a format suitable for DFT_tools scripts.
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The projectors generated by VASP require certain post-processing before
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they can be used for DMFT calculations. The most important step is to normalize
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them within an energy window that selects band states relevant for the impurity
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problem. Note that this energy window is different from the one described above
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and it must be chosen independently of the energy
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range given by `EMIN, EMAX` in INCAR.
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Currently, it is necessary to add the Fermi energy by hand as the fifth value
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in the first line of the LOCPROJ file before the next steps can be executed.
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Post-processing of `LOCPROJ` data is generally done as follows:
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The processing of projectors is performed by the program :program:`plovasp`
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invoked as
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#. Prepare an input file `<name>.cfg` (e.g., `plo.cfg`) that describes the definition
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of your impurity problem (more details below).
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| `plovasp <plo.cfg>`
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#. Extract the value of the Fermi level from OUTCAR and paste at the end of
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the first line of LOCPROJ.
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where `<plo.cfg>` is a input file controlling the conversion of projectors.
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#. Run :program:`plovasp` with the input file as an argument, e.g.:
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The format of input file `<plo.cfg>` is described in details in
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| `plovasp plo.cfg`
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This requires that the TRIQS paths are set correctly (see Installation
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of TRIQS).
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If everything goes right one gets files `<name>.ctrl` and `<name>.pg1`.
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These files are needed for the converter that will be invoked in your
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DMFT script.
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The format of input file `<name>.cfg` is described in details in
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:ref:`plovasp`. Here we just give a simple example for the case
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of SrVO3:
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@ -257,7 +301,7 @@ Option **TRANSFORM** is optional but here it is specified to extract
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only three :math:`t_{2g}` orbitals out of five `d` orbitals given by
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:math:`l = 2`.
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For the conversion to a h5 file we use on the python level (in analogy to the Wien2kConverter)::
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The conversion to a h5-file is performed in the same way as for Wien2TRIQS::
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from triqs_dft_tools.converters.vasp_converter import *
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Converter = VaspConverter(filename = filename)
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@ -265,12 +309,15 @@ For the conversion to a h5 file we use on the python level (in analogy to the Wi
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As usual, the resulting h5-file can then be used with the SumkDFT class.
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Note that the automatic detection of the correct blockstructure might fail for VASP inputs.
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This can be circumvented by increase the :class:`SumkDFT <dft.sumk_dft.SumkDFT>` threshold to e.g.::
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Note that the automatic detection of the correct block structure might
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fail for VASP inputs.
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This can be circumvented by setting a bigger value of the threshold in
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:class:`SumkDFT <dft.sumk_dft.SumkDFT>`, e.g.::
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SK.analyse_block_structure(threshold = 1e-4)
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However, only do this after a careful study of the density matrix and the dos in the wannier basis.
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However, do this only after a careful study of the density matrix and
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the projected DOS in the localized basis.
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A general H(k)
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--------------
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