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60 lines
3.1 KiB
ReStructuredText
60 lines
3.1 KiB
ReStructuredText
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.. _nio_csc:
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DFT and projections
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==================================================
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We will perform charge self-consitent DFT+DMFT calcluations for the charge-transfer insulator NiO. We still start from scratch and provide all necessary input files to do the calculations.
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VASP setup
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-------------------------------
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We start by running a simple VASP calculation to converge the charge density initially.
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Use the :ref:`INCAR`, :ref:`POSCAR`, and :ref:`KPOINTS` provided and use your
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own :file:`POTCAR` file.
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Let us take a look in the :file:`INCAR`, where we have to specify local orbitals as basis
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for our many-body calculation.
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.. literalinclude:: images_scripts/INCAR
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`LORBIT = 14` takes care of optimizing the projectors in the energy window defined
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by `EMIN` and `EMAX`. We switch off all symmetries with `ISYM=-1` since symmetries
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are not implemented in the later DMFT scripts. Finally, we select the relevant orbitals
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for atom 1 (Ni, d-orbitals) and 2 (O, p-orbitals) by the two `LOCPROJ` lines.
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For details refer to the VASP wiki on the `LOCPROJ <https://cms.mpi.univi
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e.ac.at/wiki/index.php/LOCPROJ>`_ flag. The projectors are stored in the file `LOCPROJ`.
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plovasp
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------------------------------
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Next, we postprocess the projectors, which VASP stored in the file `LOCPROJ`.
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We do this by invoking :program:`plovasp plo.cfg` which is configured by an input file, e.g., named :ref:`plo.cfg`.
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.. literalinclude:: images_scripts/plo.cfg
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Here, in `[General]' we set the basename and the grid for calculating the density of
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states. In `[Group 1]` we define a group of two shells which are orthonormalized with
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respect to states in an energy window from `-9` to `2` for all ions simultanously
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(`NORMION = False`). We define the two shells, which correspond to the Ni d states
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and the O p states. Only the Ni shell is treated as correlated (`CORR = True`), i.e.,
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is supplemented with a Coulomb interaction later in the DMFT calculation.
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Converting to hdf5 file
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-------------------------------
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We gather the output generated by :program:`plovasp` into a hdf5 archive which :program:`dft_tools` is able to read. We do this by running :program:`python converter.py` on the script :ref:`converter.py`:
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.. literalinclude:: images_scripts/converter.py
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Now we are all set to perform a dmft calculation.
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DMFT
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==================================================
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dmft script
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------------------------------
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Since the python script for performing the dmft loop pretty much resembles that presented in the tutorial on :ref:`srvo3`, we will not go into detail here but simply provide the script :ref:`nio.py`. Following Kunes et al. in `PRB 75 165115 (2007) <https://journals.aps.org/prb/abstract/10.1103/PhysRevB.75.165115>`_ we use :math:`U=8` and :math:`J=1`. Here, we use :math:`\beta=5` instead of :math:`\beta=10` to speed up the calculations.
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Local lattice Green's function for all projected orbitals
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----------------------
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We calculate the local lattice Green's function - now also for the uncorrelated orbitals, i.e., the O p states. Therefor we use :download:`NiO_local_lattice_GF.py <images_scripts/NiO_local_lattice_GF.py`
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