FeynRules - Feynman rules made easy

In this paper we present FeynRules, a new Mathematica package that facilitates the implementation of new particle physics models. After the user implements the basic model information (e.g., particle content, parameters and Lagrangian), FeynRules derives the Feynman rules and stores them in a generic form suitable for translation to any Feynman diagram calculation program. The model can then be translated to the format specific to a particular Feynman diagram calculator via FeynRules translation interfaces. Such interfaces have been written for CalcHEP/CompHEP, FeynArts/FormCalc, MadGraph/MadEvent and Sherpa, making it possible to write a new model once and have it work in all of these programs. In this paper, we describe how to implement a new model, generate the Feynman rules, use a generic translation interface, and write a new translation interface. We also discuss the details of the FeynRules code.

Program summary

Program title: FeynRulesCatalogue identifier: AEDI_v1_0Program summary URL::http://cpc.cs.qub.ac.uk/summaries/AEDI_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 15 980No. of bytes in distributed program, including test data, etc.: 137 383Distribution format: tar.gzProgramming language: MathematicaComputer: Platforms on which Mathematica is availableOperating system: Operating systems on which Mathematica is availableClassification: 11.1, 11.2, 11.6Nature of problem: Automatic derivation of Feynman rules from a Lagrangian. Implementation of new models into Monte Carlo event generators and FeynArts.Solution method: FeynRules works in two steps:

1. derivation of the Feynman rules directly form the Lagrangian using canonical commutation relations among fields and creation operators.

2. implementation of the new physics model into FeynArts as well as various Monte Carlo programs via interfaces.

Full-size table

     

FeynEdit—a tool for drawing Feynman diagrams

We describe the FeynEdit tool for drawing Feynman diagrams. Input and output is done using the macros of FeynArts, which also implies that diagrams drawn by FeynArts can be edited with FeynEdit. The code can be conveniently transferred using copy-and-paste.

Program summary

Program title: FeynEditCatalogue identifier: AEBX_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBX_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 31 729No. of bytes in distributed program, including test data, etc.: 500 240Distribution format: tar.gzProgramming language: JavaComputer: All Java-capable platformsOperating system: Linux, Mac OS, WindowsRAM: 1-2 MBytesClassification: 4.4Nature of problem: Graphical editing of Feynman diagrams.Solution method: The user copy-and-pastes the LaTeX code of the Feynman diagram into the editor, clicks a button to visualize the diagram, modifies it using the mouse, and finally copy-and-pastes it back into the text.Restrictions: Propagators are presently drawn only as straight lines. This is largely for performance reasons and may be added in a future version. It is not a serious deficit because that information can easily be added in the LaTeX code.Unusual features: Uses FeynArts' LaTeX representation for input and outputRunning time: User-dependent     

Automatic calculation of supersymmetric renormalization group equations and loop corrections

SARAH is a Mathematica package for studying supersymmetric models. It calculates for a given model the masses, tadpole equations and all vertices at tree-level. This information can be used by SARAH to write model files for CalcHep/CompHep or FeynArts/FormCalc. In addition, the second version of SARAH can derive the renormalization group equations for the gauge couplings, parameters of the superpotential and soft-breaking parameters at one- and two-loop level. Furthermore, it calculates the one-loop self-energies and the one-loop corrections to the tadpoles. SARAH can handle all N=1 SUSY models whose gauge sector is a direct product of SU(N) and U(1) gauge groups. The particle content of the model can be an arbitrary number of chiral superfields transforming as any irreducible representation with respect to the gauge groups. To implement a new model, the user has just to define the gauge sector, the particle, the superpotential and the field rotations to mass eigenstates.

Program summary

Program title: SARAHCatalogue identifier: AEIB_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIB_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 97 577No. of bytes in distributed program, including test data, etc.: 2 009 769Distribution format: tar.gzProgramming language: MathematicaComputer: All systems that Mathematica is available forOperating system: All systems that Mathematica is available forClassification: 11.1, 11.6Nature of problem: A supersymmetric model is usually characterized by the particle content, the gauge sector and the superpotential. It is a time consuming process to obtain all necessary information for phenomenological studies from these basic ingredients.Solution method: SARAH calculates the complete Lagrangian for a given model whose gauge sector can be any direct product of SU(N) gauge groups. The chiral superfields can transform as any, irreducible representation with respect to these gauge groups and it is possible to handle an arbitrary number of symmetry breakings or particle rotations. Also the gauge fixing terms can be specified. Using this information, SARAH derives the mass matrices and Feynman rules at tree-level and generates model files for CalcHep/CompHep and FeynArts/FormCalc. In addition, it can calculate the renormalization group equations at one- and two-loop level and the one-loop corrections to the one- and two-point functions.Unusual features: SARAH just needs the superpotential and gauge sector as input and not the complete Lagrangian. Therefore, the complete implementation of new models is done in some minutes.Running time: Measured CPU time for the evaluation of the MSSM on an Intel Q8200 with 2.33 GHz. Calculating the complete Lagrangian: 12 seconds. Calculating all vertices: 75 seconds. Calculating the one- and two-loop RGEs: 50 seconds. Calculating the one-loop corrections: 7 seconds. Writing a FeynArts file: 1 second. Writing a CalcHep/CompHep file: 6 seconds. Writing the LaTeX output: 1 second.     

HFOLD - A program package for calculating two-body MSSM Higgs decays at full one-loop level

HFOLD (Higgs Full One Loop Decays) is a Fortran program package for calculating all MSSM Higgs two-body decay widths and the corresponding branching ratios at full one-loop level. The package is done in the SUSY Parameter Analysis convention and supports the SUSY Les Houches Accord input and output format.

Program summary

Program title: HFOLDCatalogue identifier: AEJG_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJG_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 340 621No. of bytes in distributed program, including test data, etc.: 1 760 051Distribution format: tar.gzProgramming language: Fortran 77Computer: Workstation, PCOperating system: LinuxRAM: 524 288 000 BytesClassification: 11.1External routines: LoopTools 2.2 (http://www.feynarts.de/looptools/), SLHALib 2.2 (http://www.feynarts.de/slha/). The LoopTools code is included in the distribution package.Nature of problem: A future high-energy e⁺e⁻ linear collider will be the best environment for the precise measurements of masses, cross sections, branching ratios, etc. Experimental accuracies are expected at the per-cent down to the per-mile level. These must be matched from the theoretical side. Therefore higher order calculations are mandatory.Solution method: This program package calculates all MSSM Higgs two-body decay widths and the corresponding branching ratios at full one-loop level. The renormalization is done in the DR scheme following the SUSY Parameter Analysis convention. The program supports the SUSY Les Houches Accord input and output format.Running time: The example provided takes only a few seconds to run.     

AMBRE—a Mathematica package for the construction of Mellin-Barnes representations for Feynman integrals

The Mathematica toolkit AMBRE derives Mellin-Barnes (MB) representations for Feynman integrals in d=4−2ε dimensions. It may be applied for tadpoles as well as for multi-leg multi-loop scalar and tensor integrals. The package uses a loop-by-loop approach and aims at lowest dimensions of the final MB representations. The present version works fine for planar Feynman diagrams. The output may be further processed by the package MB for the determination of its singularity structure in ε. The AMBRE package contains various sample applications for Feynman integrals with up to six external particles and up to four loops.

Program summary

Program title:AMBRECatalogue identifier:ADZR_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZR_v1_0.htmlProgram obtainable from:CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions:standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.:21 387No. of bytes in distributed program, including test data, etc.:100 004Distribution format:tar.gzProgramming language:MATHEMATICA v.5.0 and later versionsComputer:allOperating system:allRAM:sufficient for a typical installation of MATHEMATICAClassification:5; 11.1External routines:The examples in the package use:

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MB.m [M. Czakon, Comput. Phys. Commun. 175 (2006) 559 (CPC Cat. Id. ADYG)], for expansions in ε;

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CUBA [T. Hahn, Comput. Phys. Commun. 168 (2005) 78 (CPC Cat. Id. ADVH)], for numerical evaluation of multidimensional integrals;

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CERNlib [CERN Program Library, http://cernlib.web.cern.ch/cernlib/], for the implementation of Γ and Ψ functions in Fortran.

Nature of problem:Derivation of a representation for a Feynman diagram with L loops and N internal lines in d dimensions by Mellin-Barnes integrals; the subsequent evaluation, after an analytical continuation in ε=(4−d)/2, has to be done with other packages.Solution method:Introduction of N Feynman parameters xi, integration over the loop momenta, and subsequent integration over x, introducing thereby representations of sums of monomials in x by Mellin-Barnes integrals.Restrictions:Limited by the size of the available storage space.Running time:Depending on the problem; usually seconds.     

Algorithmic derivation of Dyson-Schwinger equations

We present an algorithm for the derivation of Dyson-Schwinger equations of general theories that is suitable for an implementation within a symbolic programming language. Moreover, we introduce the Mathematica package DoDSE¹ which provides such an implementation. It derives the Dyson-Schwinger equations graphically once the interactions of the theory are specified. A few examples for the application of both the algorithm and the DoDSE package are provided.

Program summary

Program title: DoDSECatalogue identifier: AECT_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECT_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 105 874No. of bytes in distributed program, including test data, etc.: 262 446Distribution format: tar.gzProgramming language: Mathematica 6 and higherComputer: all on which Mathematica is availableOperating system: all on which Mathematica is availableClassification: 11.1, 11.4, 11.5, 11.6Nature of problem: Derivation of Dyson-Schwinger equations for a theory with given interactions.Solution method: Implementation of an algorithm for the derivation of Dyson-Schwinger equations.Unusual features: The results can be plotted as Feynman diagrams in Mathematica.Running time: Less than a second to minutes for Dyson-Schwinger equations of higher vertex functions.     

LATTICEEASY: A program for lattice simulations of scalar fields in an expanding universe

We describe a C++ program that we have written and made available for calculating the evolution of interacting scalar fields in an expanding universe. The program is particularly useful for the study of reheating and thermalization after inflation. The program and its full documentation are available on the Web at http://www.science.smith.edu/departments/Physics/fstaff/gfelder/latticeeasy/. In this paper we provide a brief overview of what the program does and what it is useful for.

Program summary

Program title: LATTICEEASYCatalog identifier: AEAW_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAW_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 2579No. of bytes in distributed program, including test data, etc.: 34 521Distribution format: tar.gzProgramming language: C++Computer: AnyOperating system: AnyRAM: Typically 4 MB to 800 MBClassification: 1.9Nature of problem: After inflation the universe consisted of interacting fields in a high energy, nonthermal state [1]. The evolution of these fields can not be described with standard approximation techniques such as linearization, kinetic theory, or Hartree expansion, and must thus be simulated numerically. Fortunately, the fields rapidly acquire large occupation numbers over a range of frequencies, so their evolution can be accurately modeled with classical field theory [2]. The specific fields and interactions relevant at these high energies are not known, so different models must be tested phenomenologically.Solution method: LATTICEEASY solves the equations of motion for interacting scalar fields in an expanding universe. The user describes a particular theory by entering the field potential and its derivatives in a “model file” and the program then uses a staggered leapfrog method to evolve the field equations and Friedmann equation for the fields and the expansion of the universe.Restrictions: In its current form LATTICEEASY only includes scalar fields and does not include metric perturbations.Running time: The running time can range from minutes to weeks.References: [1] A.D. Linde, Particle Physics and Inflationary Cosmology, Harwood, Chur, Switzerland, 1990. [2] S. Khlebnikov, I. Tkachev, Phys. Rev. Lett. 77 (1996) 219, hep-ph 9603378.     

Monte Carlo event generator for black hole production and decay in proton-proton collisions - QBH version 1.02

We describe the Monte Carlo event generator for black hole production and decay in proton-proton collisions - QBH version 1.02. The generator implements a model for quantum black hole production and decay based on the conservation of local gauge symmetries and democratic decays. The code in written entirely in C++ and interfaces to the PYTHIA 8 Monte Carlo code for fragmentation and decays.

Program summary

Program title: QBHCatalogue identifier: AEGU_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGU_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 10 048No. of bytes in distributed program, including test data, etc.: 118 420Distribution format: tar.gzProgramming language: C++Computer: x86Operating system: Scientific Linux, Mac OS XRAM: 1 GBClassification: 11.6External routines: PYTHIA 8130 (http://home.thep.lu.se/~torbjorn/pythiaaux/present.html) and LHAPDF (http://projects.hepforge.org/lhapdf/)Nature of problem: Simulate black hole production and decay in proton-proton collision.Solution method: Monte Carlo simulation using importance sampling.Running time: Eight events per second.     

ALOHA: Automatic libraries of helicity amplitudes for Feynman diagram computations

We present an application that automatically writes the Helas (HELicity Amplitude Subroutines) library corresponding to the Feynman rules of any quantum field theory Lagrangian. The code is written in Python and takes the Universal FeynRules Output (Ufo) as an input. From this input it produces the complete set of routines, wave-functions and amplitudes, that are needed for the computation of Feynman diagrams at leading as well as at higher orders. The representation is language independent and currently it can output routines in Fortran, C++, and Python. A few sample applications implemented in the MadGraph 5 framework are presented.Program summaryProgram title: ALOHACatalogue identifier: AEMS_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMS_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: http://www.opensource.org/licenses/UoI-NCSA.phpNo. of lines in distributed program, including test data, etc.: 6094320No. of bytes in distributed program, including test data, etc.: 7479819Distribution format: tar.gzProgramming language: Python2.6Computer: 32/64 bitOperating system: Linux/Mac/WindowsRAM: 512 MbytesClassification: 4.4, 11.6Nature of problem:An effcient numerical evaluation of a squared matrix element can be done with the help of the helicity routines implemented in the HELAS library [1]. This static library contains a limited number of helicity functions and is therefore not always able to provide the needed routine in the presence of an arbitrary interaction. This program provides a way to automatically create the corresponding routines for any given model.Solution method:ALOHA takes the Feynman rules associated to the vertex obtained from the model information (in the Ufo format [2]), and multiplies it by the different wavefunctions or propagators. As a result the analytical expression of the helicity routines is obtained. Subsequently, this expression is automatically written in the requested language (Python, Fortran or C++)Restrictions: The allowed fields are currently spin 0, 1/2, 1 and 2, and the propagators of these particles are canonical.Running time: A few seconds for the SM and the MSSM, and up to a few minutes for models with spin 2 particles.References:[1] Murayama, H. and Watanabe, I. and Hagiwara, K., Helas: HELicity Amplitude Subroutines for Feynman diagram evaluations, KEK-91-11, (1992) http://www-lib.kek.jp/cgi-bin/img_index?199124011[2] C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer, et al., Ufo— The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201-1214. arXiv:1108.2040, doi:10.1016/j.cpc.2012.01.022.     

HypExp 2, Expanding hypergeometric functions about half-integer parameters

In this article, we describe a new algorithm for the expansion of hypergeometric functions about half-integer parameters. The implementation of this algorithm for certain classes of hypergeometric functions in the already existing Mathematica package HypExp is described. Examples of applications in Feynman diagrams with up to four loops are given.

New version program summary

Program title:HypExp 2Catalogue identifier:ADXF_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXF_v2_0.htmlProgram obtainable from:CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions:Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.:106 401No. of bytes in distributed program, including test data, etc.:2 668 729Distribution format:tar.gzProgramming language:MathematicaComputer:Computers running MathematicaOperating system:Linux, Windows, MacRAM:Depending on the complexity of the problemSupplementary material:Library files which contain the expansion of certain hypergeometric functions around their parameters are availableClassification:4.7, 5Does the new version supersede the previous version?:YesNature of problem:Expansion of hypergeometric functions about parameters that are integer and/or half-integer valued.Solution method:New algorithm implemented in Mathematica.Reasons for new version:Expansion about half-integer parameters.Summary of revisions:Ability to expand about half-integer valued parameters added.Restrictions:The classes of hypergeometric functions with half-integer parameters that can be expanded are listed below.Additional comments:The package uses the package HPL included in the distribution.Running time:Depending on the expansion.     

A completely open source based computing system for computer generation of Fourier holograms

Computer generated holograms are usually generated using commercial software like MATLAB, MATHCAD, Mathematica, etc. This work is an approach in doing the same using freely distributed open source packages and Operating System. A Fourier hologram is generated using this method and tested for simulated and optical reconstruction. The reconstructed images are in good agreement with the objects chosen. The significance of using such a system is also discussed.

Program summary

Program title: FHOLOCatalogue identifier: AEDS_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDS_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 176 336No. of bytes in distributed program, including test data, etc.: 4 294 872Distribution format: tar.gzProgramming language: C++Computer: any X86 micro computerOperating system: Linux (Debian Etch)RAM: 512 MBClassification: 18Nature of problem: To generate a Fourier Hologram in micro computer only by using open source operating system and packages.Running time: Depends on the matrix size. 10 sec for a matrix of size 256×256.     

A recursive method to calculate UV-divergent parts at one-loop level in dimensional regularization

A method is introduced to calculate the UV-divergent parts at one-loop level in dimensional regularization. The method is based on the recursion, and the basic integrals are just the scaleless integrals after the recursive reduction, which involve no other momentum scales except the loop momentum itself. The method can be easily implemented in any symbolic computer language, and a implementation in Mathematica is ready to use.Program summaryProgram title: UVPartCatalogue identifier: AELY_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AELY_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 26 361No. of bytes in distributed program, including test data, etc.: 412 084Distribution format: tar.gzProgramming language: MathematicaComputer: Any computer where the Mathematica is running.Operating system: Any capable of running Mathematica.Classification: 11.1External routines: FeynCalc (http://www.feyncalc.org/), FeynArts (http://www.feynarts.de/)Nature of problem: To get the UV-divergent part of any one-loop expression.Solution method: UVPart is a Mathematica package where the recursive method has been implemented.Running time: In general it is below one second.     

The implementation of the renormalized complex MSSM in FeynArts and FormCalc

We describe the implementation of the renormalized complex MSSM (cMSSM) in the diagram generator FeynArts and the calculational tool FormCalc. This extension allows to perform UV-finite one-loop calculations of cMSSM processes almost fully automatically. The Feynman rules for the cMSSM with counterterms are available as a new model file for FeynArts. Also included are default definitions of the renormalization constants; this fixes the renormalization scheme. Beyond that all model parameters are generic, e.g. we do not impose any relations to restrict the number of input parameters. The model file has been tested extensively for several non-trivial decays and scattering reactions. Our renormalization scheme has been shown to give stable results over large parts of the cMSSM parameter space.     

Visual tool for estimating the fractal dimension of images

This work presents a new Visual Basic 6.0 application for estimating the fractal dimension of images, based on an optimized version of the box-counting algorithm. Following the attempt to separate the real information from “noise”, we considered also the family of all band-pass filters with the same band-width (specified as parameter). The fractal dimension can be thus represented as a function of the pixel color code. The program was used for the study of paintings cracks, as an additional tool which can help the critic to decide if an artistic work is original or not.

Program summary

Program title: Fractal Analysis v01Catalogue identifier: AEEG_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEG_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 29 690No. of bytes in distributed program, including test data, etc.: 4 967 319Distribution format: tar.gzProgramming language: MS Visual Basic 6.0Computer: PCOperating system: MS Windows 98 or laterRAM: 30MClassification: 14Nature of problem: Estimating the fractal dimension of images.Solution method: Optimized implementation of the box-counting algorithm. Use of a band-pass filter for separating the real information from “noise”. User friendly graphical interface.Restrictions: Although various file-types can be used, the application was mainly conceived for the 8-bit grayscale, windows bitmap file format.Running time: In a first approximation, the algorithm is linear.     

Motion4D - A library for lightrays and timelike worldlines in the theory of relativity

The Motion4D-library solves the geodesic equation as well as the parallel- and Fermi-Walker-transport in four-dimensional Lorentzian spacetimes numerically. Initial conditions are given with respect to natural local tetrads which are adapted to the symmetries or the coordinates of the spacetime. Beside some already implemented metrics like the Schwarzschild and Kerr metric, the object oriented structure of the library permits to implement other metrics or integrators in a straight forward manner.

Program summary

Program title: Motion4D-libraryCatalogue identifier: AEEX_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEX_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 150 425No. of bytes in distributed program, including test data, etc.: 5 139 407Distribution format: tar.gzProgramming language: C++Computer: All platforms with a C++ compilerOperating system: Linux, Unix, WindowsRAM: 39 MBytesClassification: 1.5External routines: Gnu Scientific Library (GSL) (http://www.gnu.org/software/gsl/)Nature of problem: Solve geodesic equation, parallel and Fermi-Walker transport in four-dimensional Lorentzian spacetimes.Solution method: Integration of ordinary differential equationsRunning time: The test runs provided with the distribution require only a few seconds to run.     

xPerm: fast index canonicalization for tensor computer algebra

We present a very fast implementation of the Butler-Portugal algorithm for index canonicalization with respect to permutation symmetries. It is called xPerm, and has been written as a combination of a Mathematica package and a C subroutine. The latter performs the most demanding parts of the computations and can be linked from any other program or computer algebra system. We demonstrate with tests and timings the effectively polynomial performance of the Butler-Portugal algorithm with respect to the number of indices, though we also show a case in which it is exponential. Our implementation handles generic tensorial expressions with several dozen indices in hundredths of a second, or one hundred indices in a few seconds, clearly outperforming all other current canonicalizers. The code has been already under intensive testing for several years and has been essential in recent investigations in large-scale tensor computer algebra.

Program summary

Program title: xPermCatalogue identifier: AEBH_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBH_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 93 582No. of bytes in distributed program, including test data, etc.: 1 537 832Distribution format: tar.gzProgramming language: C and Mathematica (version 5.0 or higher)Computer: Any computer running C and Mathematica (version 5.0 or higher)Operating system: Linux, Unix, Windows XP, MacOSRAM:: 20 MbyteWord size: 64 or 32 bitsClassification: 1.5, 5Nature of problem: Canonicalization of indexed expressions with respect to permutation symmetries.Solution method: The Butler-Portugal algorithm.Restrictions: Multiterm symmetries are not considered.Running time: A few seconds with generic expressions of up to 100 indices. The xPermDoc.nb notebook supplied with the distribution takes approximately one and a half hours to execute in full.     

MDVRY: a polarizable classical molecular dynamics package for biomolecules

The MDVRY classical molecular dynamics package is presented for the study of biomolecules in the gas and liquid phase. Electrostatic polarization has been implemented in the formalism of point induced dipoles following the model of Thole. Two schemes have been implemented for the calculation of induced dipoles, i.e. resolution of the self-consistent equations and a ‘Car-Parrinello’ dynamical approach. In this latter, the induced dipoles are calculated at each time step of the dynamics through the dynamics of additional degrees of freedom associated with the dipoles. This method saves computer time and allows to study polarized solvated proteins at a very low CPU cost. The program is written in C-language and runs on LINUX machines. A detailed manual of the code is given. The main features of the package are illustrated taking on examples of proteins in the gas phase or immersed in liquid water.

Program summary

Program title: MDVRYCatalogue identifier: AEBY_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBY_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 39 156No. of bytes in distributed program, including test data, etc.: 277 197Distribution format: tar.bz2Programming language: CComputer: Linux machines with FFTW Fourier Transform package installedOperating system: Linux machines, SUSE & RedHat distributionsClassification: 3, 16.13, 23External routines: FFTW (http://www.fftw.org/)Nature of problem: Molecular Dynamics Software package.Solution method: Velocity Verlet algorithm. The implemented force field is composed of intra-molecular interactions and inter-molecular interactions (electrostatics, polarization, van der Waals). Polarization is accounted through induced point dipoles at each atomic site. Supplementary degrees of freedom are associated to the induced dipoles so that a modified Hamiltonian of the dynamics is written. This allows to calculate the induced dipoles with a very fast ‘Car-Parrinello’ type of dynamics.Running time: The test run provided takes approximately 6 minutes to run.