Orbital construction and conversion for DMFT method

The first step for a DMFT calculation is to provide the necessary input based on a DFT calculation. We will not review how to do the DFT calculation here in this documentation, but refer the user to the documentation and tutorials that come with the actual DFT package. Here, we will describe how to use output created by Wien2k, as well as how to use the light-weight general interface.

Interface with Wien2k

We assume that the user has obtained a self-consistent solution of the Kohn-Sham equations. We further have to require that the user is familiar with the main in/output files of Wien2k, and how to run the DFT code.

Conversion for the DMFT self-consistency cycle

First, we have to write the necessary quantities into a file that can be processed further by invoking in a shell the command

x lapw2 -almd

We note that any other flag for lapw2, such as -c or -so (for spin-orbit coupling) has to be added also to this line. This creates some files that we need for the Wannier orbital construction.

The orbital construction itself is done by the Fortran program dmftproj. For an extensive manual to this program seeTutorialDmftproj.pdf. Here we will only describe the basic steps.

Let us take the compound SrVO3, a commonly used example for DFT+DMFT calculations. The input file for dmftproj looks like

3                ! Nsort
1 1 3            ! Mult(Nsort)
3                ! lmax
complex          ! choice of angular harmonics
1 0 0 0          ! l included for each sort
0 0 0 0          ! If split into ireps, gives number of ireps. for a given orbital (otherwise 0)
cubic            ! choice of angular harmonics
1 1 2 0          ! l included for each sort
0 0 2 0          ! If split into ireps, gives number of ireps. for a given orbital (otherwise 0)
01               !
0                ! SO flag
complex          ! choice of angular harmonics
1 1 0 0          ! l included for each sort
0 0 0 0          ! If split into ireps, gives number of ireps. for a given orbital (otherwise 0)
-0.11 0.14

The first three lines give the number of inequivalent sites, their multiplicity (to be in accordance with the Wien2k struct file) and the maximum orbital quantum number lmax. In our case our struct file contains the atoms in the order Sr, V, O.

Next we have to specify for each of the inequivalent sites, whether we want to treat their orbitals as correlated or not. This information is given by the following 3 to 5 lines:

To continue click on the link below:

https://triqs.ipht.cnrs.fr/applications/dft_tools/guide/conversion.html?highlight=wien2k