ALF  dev.
A QMC Code for fermionic models
ALF

Project website: https://alf.physik.uni-wuerzburg.de/.

-> Interested contributors please check our https://git.physik.uni-wuerzburg.de/ALF/ALF/-/blob/master/CONTRIBUTING.md "CONTRIBUTING.md" guidelines.

-> This is the development version of ALF, the latest stable version is ALF 2.3.

Description

The **A**lgorithms for **L**attice **F**ermions package provides a general code for the finite temperature and projective auxiliary field Quantum Monte Carlo algorithm. The code is engineered to be able simulate any model that can be written in terms of sums of single body operators, of squares of single body operators and single body operators coupled to an Ising field with given dynamics. We provide predefined types that allow the user to specify the model, the Bravais lattice as well as equal time and time displaced observables. The code supports an MPI implementation. Examples such as the Hubbard model, the SU(N) Kondo lattice model, tV models, models with long ranged interactions as well as Z2 lattice gauge theories coupled to fermions adn Z2 matter are discussed in the documentation. Slides on the auxiliary field QMC can be found here.

The Hamiltonians we can consider read:

Hamiltonian0.png
The Hamiltonian0

where

Hamiltonian1.png
The Hamiltonian1

Here Z denotes a scalar field (Ising or real continuous field) with predefined dynamics. If your model can be written in this form then it will be amenable to the ALF.

pyALF

For ease of use, the pyALF repository provides a python interface to run the ALF-code

Doxygen

You can find here Doxygen formatted documentation. (Work in progress)

Installation

PREREQUISITES

CONFIGURATION FOR COMPILATION

configure.sh It is recommended to use this script to set the environment variables. Type ./configure.sh to browse through a list of options. Notice that directory names containing spaces are not supported.

Once you have run the configuration script, change directory to Libraries, and to Analysis and run the Makefiles there. In the Prog directory then type make examples. The other programs are being updated to comply with the new version of the code.

FILES AND DIRECTORIES

Libraries Libraries. Once that the environment is set in the file configure.sh the Libraries can be compiled with the make command.

Prog Main program and subroutines.

Analysis Analysis programs.

Scripts_and_Parameters_files Helper scripts and the Start/ directory, which contains the files required to start a run.

Documentation We have included in the file doc.pdf an extensive documentation.

testsuite An automatic test suite for various parts of the code

TESTING

We have about 30 tests that test various parts of the program in the folder testsuite. As testing framework we employ CTest. From the subfolder testsuite the tests can be run as follows

LICENSE

The various works that make up the ALF project are placed under licenses that put a strong emphasis on the attribution of the original authors and the sharing of the contained knowledge. To that end we have placed the ALF source code under the GPL version 3 license and took the liberty as per GPLv3 section 7 to include additional terms that deal with the attribution of the original authors (see license.GPL and license.additional). The Documentation of the ALF project by the ALF contributors is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License (see Documentation/license.CCBYSA). Note that we link against parts of lapack, which is licensed under a BSD license (see license.lapack).

KNOWN ISSUES

We have detected a bug in both 2017 versions of Intel's MPI implementation (mpi.intel/2017(default) and mpi.intel/2017.2) if used in combination with the parallel (threaded) MKL library. The advise is to use either the 2016 suite (intel/16.0 (compiler), mpi.intel/5.1 and mkl/11.3 ) or the new 2018 suite (intel/18.0 (compiler), mpi.intel/2018 and mkl/2018). We did not detect this issue in both environments. You should also be aware the by default, dynamic linking is used. Hence if you use the 2016 or 2018 modules at compilations, the bug can reenter if you still load the 2017 versions at runtime. So please adapt your configureHPC.sh as well as your Jobfiles for the loadleveler accordingly. Additional note: In the serial version, the bug also seems to be absent. If you want to use the 2017 suite, you have to use the serial version of MKL (mkl/2017_s), which means you cannot profit from openMP multi-threading. This library is linked statically, hence taking care of this at compile time is sufficient and there is no need to adapt the Jobfiles. WARNING: Even if you do not use parallel tempering actively, we still strongly suggest to take care of the above bug as it is extremely hard to estimate hidden influences and correlations of this memory allocation bug in the rest of the program. It is possible the other parts of the algorithm might be affected apart from the tempering exchange step even so we have absolutely no hint of additionally affected sections in ALF.

Intel suite 2017: Apparently, there seems to be a bug in the Intel MPI threaded memory allocator if both Intel MPI implementation and the PARALLEL version of MKL is used. This bug corrupts the data transmission during tempering moves such that the Monte Carlo is broken. The current advise is to either use an earlier version (2016 and before) or a newer one (2018 and later). It should also be OK to use the sequential MKL library if openMP multi-threading is not required. Setting the environment variable OMP_NUM_THREADS=1 however does not fix the bug as this still uses the threaded MKL library (Date: 1. June 2018)