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41 lines
2.6 KiB
ReStructuredText
41 lines
2.6 KiB
ReStructuredText
.. _Sr2RuO4:
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Spin-orbit coupled calculations (single-shot)
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=============================================
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There are two main ways of including the spin-orbit coupling (SO) term into
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DFT+DMFT calculations:
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- by performing a DFT calculation including SO and then doing a DMFT calculation on top, or
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- by performing a DFT calculation without SO and then adding the SO term on the model level.
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Treatment of SO in DFT
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----------------------
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For now, TRIQS/DFTTools does only work with Wien2k when performing calculations with SO.
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Of course, the general Hk framework is also possible.
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But the way VASP treats SO is fundamentally different to the way Wien2k treats it and the interface does not handle that at the moment.
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Therefore, this guide assumes that Wien2k is being used.
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First, a Wien2k calculation including SO has to be performed.
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For details, we refer the reader to the documentation of Wien2k.
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The interface to Wien2k only works when the DFT calculation is done both spin-polarized and with SO (that means that you have to initialize the Wien2k calculation accordingly and then run with ``runsp -sp``).
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Performing the projection
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Note that the final ``x lapw2 -almd -so -up`` and ``x lapw2 -almd -so -dn`` have to be run *on a single core*, which implies that, before, ``x lapw1 -up``, ``x lapw2 -dn``, and ``x lapwso -up`` have to be run in single-core mode (once).
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In the ``case.indmftpr`` file, the spin-orbit flag has to be set to ``1`` for the correlated atoms.
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For example, for the compound Sr\ :sub:`2`\ RuO\ :sub:`4`, with the struct file :download:`Sr2RuO4.struct <Sr2RuO4/Sr2RuO4.struct>`, we would e.g. use the ``indmftpr`` file :download:`found here <Sr2RuO4/Sr2RuO4.indmftpr>`.
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Then, ``dmftproj -sp -so`` has to be called.
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As usual, it is important to check for warnings (e.g., about eigenvalues of the overlap matrix) in the output of ``dmftproj`` and adapt the window until these warnings disappear.
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Note that in presence of SO, it is not possible to project only onto the :math:`t_{2g}` subshell because it is not an irreducible representation.
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A redesign of the orthonormalization procedure might happen in the long term, which might allow that.
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We strongly suggest using the :py:meth:`.dos_wannier_basis` functionality of the :py:class:`.SumkDFTTools` class (see :download:`calculate_dos_wannier_basis.py <Sr2RuO4/calculate_dos_wannier_basis.py>`) and compare the Wannier-projected orbitals to the original DFT DOS (they should be more or less equal).
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Note that, with SO, there are usually off-diagonal elements of the spectral function, which can also be imaginary.
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The imaginary part can be found in the third column of the files ``DOS_wann_...``.
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