The DL_POLY Molecular Simulation Package
02 May 2017
- Ilian Todorov







​General Information​​​​​

DL_POLY is a general purpose classical molecular dynamics (MD) simulation software developed at Daresbury Laboratory by I.T. Todorov and W. Smith.

Currently, only one version of the DL_POLY software is available under an STFC licence, DL_POLY_4, and with support provisioned to the UK's academia only. The former DL_POLY_2 version (authored by W. Smith, T.R. Forester and I.T. Todorov) is now transformed into DL_POLY_CLASSIC (link opens in a new window) and available as open source under the BSD (link opens in a new window) at CCPForge (link opens in a new window).

DL_POLY_4 general design provides scalable performance from a single processor workstation to a high performance parallel computer.  It is supplied in source form under licence and can be compiled as a serial application code, using only a Fortran90 compiler, or as a parallel application code, provided an MPI2 instrumentation is available on the parallel machine.  DL_POLY_4 offers fully parallel I/O as well as a netCDF alternative (HDF5 library dependence) to the default ASCII trajectory file.

For more information, suggestions and feedback on specific DL_POLY_4 components such as

The package is the property of STFC (link opens in a new window).

The grossular garnet cell of Ca3Si3Al2O12 showing the SiO4 as yellow tetrahedra and the AlO6 as purple octahedra
(Credit: Colin L. Freeman)​

Software & Licensing

DL_POLY_4 is the direct successor of DL_POLY_3 (I.T. Todorov and W. Smith) which also incorporates concepts and functionality from DL_POLY_2 (W. Smith, T.R. Forester and I.T. Todorov).  Like DL_POLY_3, DL_POLY_4 parallelisation is based on the static/equi-spatial Domain Decomposition (DD) model.  It enables an excellent load-balancing and parallel performance provided that:

  • The particle density of the modelled system is close to uniform in space and time (ensuring load balancing)
  • The system dimensions per processor/domain are no smaller than the largest system cutoff, preferably no smaller than three times (ensuring good parallel performance).

Future plans include a hybridisation from purely MPI mapped DD to usage of OpenMP threading within the MPI framework for better per core performance and improved load balance (LB) of the DD strategy.

A full description of the available DL_POLY_4 functionality may be obtained from the DL_POLY_4 User Manual (PDF) (PDF - link opens in a new window).

A description of the complementary DL_POLY GUI and its functionality may be obtained from the DL_POLY_4 GUI Manual (PDF) (PDF - link opens in a new window).

DL_POLY_4 is supplied to individuals under an academic licence, which is free of cost to academic scientists pursuing scientific research of a non-commercial nature. Please, see the web page Registering for the DL_POLY_4 Package for instructions.  Commercial organisations interested in acquiring the package should approach Dr Ilian Todorov at Daresbury Laboratory in the first instance.  Daresbury Laboratory is the sole centre for distribution of the package.

Valinomycin at a Pseudo-Membrane Surface
(Credit: W. Smith & T.R. Forester)

Software Design

The DL_POLY_4 code design is based on the principles of portability, maintenance, transparency and user verification.  The code architecture adopts the Fortran90 modularisation in a C/C++ header style manner, where concepts and functionality are separated in a functional way by modules.  The code routines relate to features/actions by their file names, which often relate to module names.

The DL_POLY_4 vanilla source is in fully self-contained, free-formatted Fortran90+MPI2 code (specifically Fortran90 + TR15581 + MPI1 + MPI-I/O only). The vanilla distribution complies with the NAGWare (link opens in a new window) and FORCHECK (link opens in a new window) Fortran90 standards with exception of the Fortran2003 feature known as TR15581, which is very rarely unavailable in the current Fortran95 compilers.

Extensions such as the netCDF I/O and openKIM functionality break this self-containment as they each add additional dependences.

Off-lattice representation of oligosaccharide (larger semi-transparent spheres) superimposed on corresponding atomic configuration
(Credit: Dmytro Antypov (PDF - link opens in a new window))​

History & Funding

The DL_POLY project was originally conceived in 1993 by William Smith at the Molecular Simulation Group (now part of the Computational Chemistry Group, MSG) at Daresbury Laboratory under the auspices of the Engineering and Physical Sciences Research Council (EPSRC (link opens in a new window)) for the EPSRC's Collaborative Computational Project for the Computer Simulation of Condensed Phases (CCP5 (link opens in a new window)).  EPSRC's funding drove the DL_POLY_2 development (T.R. Forester) between 1993-1996.  The Natural Environment Research Council (NERC (link opens in a new window)) helped the DL_POLY_3 development (I.T. Todorov) through the eMinerals (link opens in a new window) project between 2003-2007.  Recently, the DL_POLY_4 project development has been driven by EPSRC's distributed/embeded Computational Science and Engineering (d/eCSE) grants provided by EPCC (link opens in a new window) (and previously by NAG Ltd. (link opens in a new window)).


Support & Collaborations

DL_POLY_4 is a UK flagship project.  The authors provide support, expertise and development effort nationally on a collaborative basis provided funding is available. UK-wide workshops are the common way of dissemination of training and expertise.  These are organised in collaboration with the authors and funded by the hosting organisation, such as an academic institution, Research Council (including STFC) or an academic community (such as CCP5, PRACE, etc.).

International (overseas) academic users are welcome to attend DL_POLY training workshops in the UK.  However, UK hosting institutions may charge attendees that are not UK based academic researchers.  International as well as UK based reserchers will find that the DL_POLY community list (link opens in a new window) at JISC. is the best way to get started and find help from the DL_POLY world-wide community.

The authors do not provide support for third party ports of the DL_POLY_4 package even though such ports are made available to users via the DL_POLY FTP server.

Users, as well as potential project contributors, are encouraged to read the ​ Code of Conduct for DL_Software Users.

International institutions interested in collaboration and/or organising home based training workshops are welcome to get in touch with Dr Ilian Todorov.

If you wish to contribute feature developments that are not yet provided with the default functionality of DL_POLY_4 or DL_POLY_Classic, please email Dr Ilian Todorov a description and user instructions of the feature together with the program code and example input files testing it.

Collaboration Projects

The protein Ovocleidin-17 binding to an amorphous calcium carbonate surface. The particular amino acid residues that bind to the surface are highlighted with a space-filling model.
(Credit: Colin L. Freeman)​
GABA_A side view (left), top view (top right) and GABA bound to its binding site in GABA_A (bottom right)
(Credit: P.-L. Chau (link opens in a new window))​
Contact: Todorov, Ilian (STFC,DL,SC)