An overview of the DMFT method as implemented within eDMFT code interfaced with wien2k code

The DMFT method is used to calculate the physical properties for the correlated systems. DMFT was originally developed [2] in the context of the Hubbard model considering the limit of large dimensions [12] (or connectivity), where DMFT becomes exact, but later it's managed to be consistent with Luttinger-Ward approach.

For more information upon the DMFT with new approach check the following link:

http://hauleweb.rutgers.edu/tutorials/whatis/whatis.html

The new version of the DMFT method as working within the Luttinger-Ward approach is implemented within the code called eDMFT.

To know how to use the DMFT method within the eDMFT code read the following picture

To know how does the DMFT method work with the wien2k code check the following pictures:

DFT within wien2k without DMFT

The DFT steps:

• lapw0: calculates electronic potential
• lapw1: solves eigenvalue problem for Kohn-Sham orbitals
• lapwso: adds spin-orbit coupling
• lapw2: calculates DFT valence electronic charge
• core: adds core states to DFT charge
• mixer: mixes electronic charge density

The DMFT+DMFT inserts two new steps (dmft1 and impurity solver) and replaces lapw2 with dmft2 step. The process looks like that:

DFT within wien2k with DMFT method

The eDMFT steps are:

• lapw0: calculates electronic potential
• lapw1: solves eigenvalue problem for Kohn-Sham orbitals
• lapwso: adds spin-orbit coupling
• dmft1: calculates local green's function and hybridization function
• impurity: solves the auxiliary impurity problem for electronic self-energy correction
• dmft2: calculates DMFT+DFT valence electronic charge
• core: adds core states to DFT charge
• mixer: mixes electronic charge density

For more information on how does the eDMFT code work check the following link:

http://hauleweb.rutgers.edu/tutorials/Overview.html

Downloading the eDMFT code

The program consists of many independent programs and executables, which are written in C++, fortran90, and Python. Here you can download its

tarball.

Installing the eDMFT code

To install the code you need to download some packages:

• C++ compiler (either gnu or intel)
• fortran compiler (either gnu or intel)
• Python (version 2) with numpy and scipy as well as weave (the latter became stand alone package, separate from scipy, after scipy 0.14 version)
• blas/lapack library (intel mkl or similar). If installation does not find it, it will try to download it and install it. You will be prompted.
• gsl library: gnu scienific library. If you do not have it, you will be prompted to do download and install it.
• fftw library for fast Fourier transform
• Finally, Wien2K needs to be installed to run charge self-consistent calculations.

The simplest type of compilation (after un-taring the code tar xzvf EDMFTF.tgz) consist of running the python setup script, i.e.,

python setup.py

To clean the previous compilation (all object files and libraries, but not removing the final binary files), you should type

python setup.py --clean

However, before you start compilation, it is advisable to first edit configure.py file, which contains information about existing libraries. There are several examples of the configuration script provided, for example, configure.py.macos, configure.py.intel, configure.py.gnu. If you are trying the code on MacOS, simply copy configure.py.macos to configure.py. On system with all intel compilers one can copy configure.py.intel to configure.py and then run python setup.py.

For more details check the following link:

http://hauleweb.rutgers.edu/tutorials/Installation.html

After the installation is complete, the following variables should be set in your .bashrc (or equivalent):

WIEN_DMFT_ROOT
PYTHONPATH
WIENROOT
SCRATCH
EDITOR

The last three should be specified during Wien2k installation, and in general do not need to be changed now. It is however advisable to set SCRATCH to current directory. For example, typical installation will have the following variables set to

export WIEN_DMFT_ROOT=$HOME/EDMFT/bin  
export PYTHONPATH=$PYTHONPATH:$WIEN_DMFT_ROOT  
export WIENROOT=$HOME/wien2k
export SCRATCH="." 
export EDITOR="emacs -nw"
export PATH=$WIENROOT:$WIEN_DMFT_ROOT:$PATH 

The properties calculated by the eDMFT code:


total free energy and forces in the presence of strong correlations
exact double-counting of DMFT and LDA
non-collinear magnetism
theoretical spectroscopies, such as optics, resistivity, neutron structure factor, resonant elastic X-ray scattering
several solvers: continuous time quantum Monte Carlo, NCA, OCA
extreme parallelism (scales up to 100,000 cores) using Message Passing Interface (MPI)
parallel execution by OpenMP


To execute the eDMFT code there are many tutorials as follows:

First Tutorial: Learn how to use the CTQMC impurity solver


Tutorial 1: MnO



Tutorial 2: FeSe and optimization of the structure


Tutorial 6: Sr2IrO4, large spin-orbit and non-collinear magnetism