ISPT
Instantaneous stochastic perturbation theory
Weak-coupling perturbation theory remains an important tool in lattice
field theory, but rapidly becomes extremly tedious beyond the first few
orders in the couplings. Numerical stochastic perturbation theory allows
the computations to be automatized and can be a viable way to proceed in
many cases.
Trivializing map
The form of stochastic perturbation theory described in the
paper
M. Lüscher,
Instantaneous stochastic perturbation theory,
JHEP 1504 (2015) 142,
is based on the concept of a
trivializing map, where the
stochastic fields simulating the theory are obtained instantaneously
rather than through a Markov process. The functionality provided by the
program package that can be downloaded from this page includes the
automatic construction of the trivializing map in the φ^4 theory and
in QCD with any number of mass-degenerate quarks.
Simulation program
Currently the only supported theory is the SU(3) gauge theory on
4-dimensional N0xN1xN2xN3
lattices with even sizes N0,...,N3, Schrödinger
functional (SF) or open-SF boundary conditions in the time direction and
periodic boundary conditions in the space directions. The gauge action is
set to the tree-level O(a)-improved Wilson plaquette action.
Program features
The programs that construct the trivializing map are serial ones written
in C. They require the
GNU Multiple Precision Arithmetic Library,
but otherwise comply with the ISO C89 (formerly ANSI C) standard.
The gmp library is freely available on practically any platform.
The simulation programs parallelize in 0,1,2,3 or 4 dimensions, depending
on what is specified at compilation time. They are highly optimized for
machines with current Intel or AMD processors, but will run correctly on
any system that complies with the ISO C89 (formerly ANSI C) and the MPI
1.2 standards.
For the purpose of testing and code development, the programs can
also be run on a desktop or laptop computer. All what is needed for
this is a compliant C compiler and a local MPI installation such as
Open MPI.
Compilation
The compilation of the programs requires an ISO C89 compliant
compiler and the gmp library mentioned above.
In the main and devel directories, a GNU-style Makefile is included
which compiles and links the programs (type "make" to compile
everything; "make clean" removes the files generated by "make").
Documentation
The programs have a modular form, with strict prototyping and a
minimal use of external variables. Each program file contains a
small number of externally accessible functions whose
functionality is described at the top of the file.
The data layout is explained in various README files and detailed
instructions are given on how to run the main programs. A set of
further documentation files are included in the doc directory.
Download
The publicly available ISPT releases are
ISPT-1.0.tar.gz (latest stable release)
ISPT-0.1.tar.gz
The package contains the source code, usage instructions and other
documentation files. After unpacking, first read the README file in
the top directory.
License
The software may be used under the terms of the
GNU General Public Licence (GPL)
.
Last updated 20 March 2017