An LA-SiGMA Software Distribution MO-IPT package Version 0.9 - May 2014 Copyright 2014 Jawaharlal Nehru Centre for Advanced Scientific Research This package contains code and sample data for generating Green's functions and self-energies of multi-orbital strongly correlated electron systems within dynamical mean field theory. The impurity solver is multi-orbital iterated perturbation theory. Detailed installation and operation instructions and other files may be found in the docs subdirectory. The code employs parallelization through message passing interface. For the latest version and other resources visit [blank, needs to be filled]. --------------------------------------------------------------------- Description MO-IPT stands for multi-orbital iterated perturbation theory. The present code implements the MO-IPT solver as described in Dasari et al [paper reference] within the dynamical mean field theory (DMFT) framework and may be used to obtain single- -particle spectra and self-energies for strongly correlated model Hamiltonians as well as real materials with multiple orbital degrees of freedom. The code is implemented for zero as well as finite temperatures. The impurity solver uses the second-order self-energy in an ansatz motivated by the continued fraction expansion of the self- -energy. The ansatz has certain free parameters that are chosen to satisfy high frequency and the atomic limits. Since the ansatz reproduces low frequency Fermi liquid behaviour and the band limit by construction, the MO-IPT is expected to be a reasonable interpolating approximation. Naturally, the MO-IPT cannot be expected to be accurate close to phase transitions, etc, where exact methods such as QMC and NRG would be far more accurate. For extensive benchmarking of the method with continuous time Monte Carlo and other methods, please see Dasari et al [paper reference]. One of the main limitations of the code is that the Hund's coupling is presently implemented only as a density-density interaction. The main merits of the MO-IPT is that it is fast, numerically inexpensive, can deal with many orbitals, and provides real frequency results at zero and finite temperature. The main motivation of our implementation is to carry out first principles calculations of strongly correlated materials, so the integration with band structure results (from e.g WIEN2K) is also implemented in this set of codes. The basic single-orbital IPT code was developed by N.S.Vidhyadhiraja (nsvraja@gmail.com). The multi-orbital extension and MPI wrapper for k-summation were done by Nagamalleswararao Dasari (nagamalleswararao.d@gmail.com). The optimization and benchmarks were carried out by Dasari, Peng (zpantz@gmail.com) and Wasim (wasimr.mondal@gmail.com) with the assistance of Mark Jarrell (jarrellphysics@gmail.com), Juana Moreno (moreno@phys.lsu.edu) and N.S.Vidhyadhiraja. Detailed operating instructions, testing procedure and physics description of the test data can be found in doc/manual.pdf. Sketchy details of the prerequisites, setup and operation are given in docs/instructions.txt and a more detailed manual is docs/manual.pdf. --------------------------------------------------------------------- Prerequisites MO-IPT has been tested on the following system: (1) Ubuntu on Intel Xeon Hex-core E5645 (2.4GHz) with 12GB RAM Linux 3.2.0-23-generic 36 -Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x8664 x8664 x8664 GNU/Linux DISTRIB ID=Ubuntu DISTRIB RELEASE = 12.04 DISTRIB CODENAME=precise Compiler information : mpif90 for MPICH version 3.0.3; ifort version 13.0.0 (2) Mageia on Intel Core i7-4765T (2GHz) with 8GB RAM Linux 3.10.28-desktop-1.mga3 #1 SMP Sat Feb 1 16:15:10 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux Distributor ID: Mageia Description: Mageia 3 Release: 3 Codename: thornicroft Compiler information : mpif90 for MPICH2 version 1.2.1; ifort version 14.0.1 MO-IPT requires an MPI implementation e.g through MPICH2 or openmpi. --------------------------------------------------------------------- Steps - Initial Setup and Simple Run These steps are for setup, and for running the code. The sample commands are for a user with home directory "/home/username" and who has unpacked the MO-IPT distribution into directory MO-IPT, so that the path to the readme file would be /home/username/MO-IPT/docs/README. [ ] Install Prerequisites (MPI) Download the MO-IPT package. Unpack using the following commands: tar -xzvf MO-IPT.tar.gz Presumably you have already done this, otherwise you wouldn't be seeing this! [ ] Build the executable. Commands: % cd /home/username/MO-IPT/src % make # This should result in an executable named MO-IPT.run % cd .. [ ] For running the code with the sample data, we recommend using the script run.sh % chmod 744 run.sh % ./run.sh Users should refer to the example description given in the manual (docs/manual.pdf). --------------------------------------------------------------------- Operation The MO-IPT package is used for finding the Green's functions and self-energies of multi-orbital strongly correlated electron systems. The execution is through command line as mentioned above. The input and output files and parameters are mentioned in docs/manual.pdf. We recommend that users should save the output appearing on stdout (display). This may be done for example by "mpirun -np $nprocs MO-IPT.run > screen.out" or "mpirun -np $nprocs MO-IPT.run | tee screen.out". The screen output is very valuable for diagnostics. If pre-existing data is used to initialise a run, then those files will be overwritten on completion. Convergence along with DMFT loop numbers appears on the screen. Users can tune the tolerance for convergence in the main.f program.