LAMMPS Windows Installer Repository

This repository is hosting pre-compiled Windows installers of the LAMMPS molecular dynamics simulation software package. The binaries are built with MinGW64 Linux to Windows cross-compilers on Fedora Linux using the standard LAMMPS sources. The LAMMPS binaries contain all optional packages included in the source distribution except:

The serial executable additionally does not contain the LATBOLTZ package, since it requires MPI-IO functions, which are not available without linking to a real MPI library.

Starting with the 17 February 2022 version of LAMMPS the KOKKOS package with the serial and OpenMP backends enabled is included. GPU support for Kokkos is currently not possible for these packages due to compiling the binaries with a cross-compiler.

Plugin Packages for Additional LAMMPS Packages

As of LAMMPS version 23 June 2022, we have started to provide add-on installer packages that contain LAMMPS packages as plugins. Those are separate packages because either their source code is not part of the LAMMPS distribution or uses and external library with licensing terms that prohibits linking the package into the LAMMPS executable and library directly. There are two variants of the plugin packages: one with support for MPI and one without. The corresponding LAMMPS installer packages have the PLUGIN package included and are set up to automatically load such plugins immediately at runtime as shown in the picture to the right.

The LAMMPS Python module (to call LAMMPS from Python) is included in all packages in a way, that it should work with a suitable Python installation of your own, since a LAMMPS shared library (i.e. a DLL file on Windows) is included. The PYTHON package (to call Python from LAMMPS) however, is only included in the installer package with Python in the name. Those packages also include a full Python runtime environment with all standard Python modules and the NumPy module since those have to be consistent with the Python library used to compile LAMMPS. Please note that the 64-bit Windows NumPy module is considered very experimental and thus one should expect crashes that are not bugs in LAMMPS.

Important Note on Microsoft Defender and Other Virus Scanners Reporting Trojans or Viruses

Sometimes virus scanners will report that the LAMMPS installer packages contain a Trojan or Virus. If you downloaded the installer from this website and get a match for the SHA-256 checksums, then the report is most likely a false positive. This can happen with installer packages like the ones provided here, since they are applications with interpreted byte code that triggers the false positive. The installer packages are created with a cross-compiler on a protected Linux machine using authenticated development tools, so it is close to impossible to produce infected packages.

If you come across such a case, please report the false positive to the antivirus vendor. You can usually then tell the virus scanner software to ignore the virus report and execute or restore the installer package anyway and install LAMMPS. However, we only recommend to do this, if you downloaded the package from the lammps.org domain and have verified the checksum to make certain you have an unmodified file. We cannot prevent malicious people from building LAMMPS installer packages that *do* contain malware, however unlikely it may seem.

Important Notes on Changes to the Installer Packages

Starting with the 2 August 2023 stable release, we have reduced the number of compiled variants. All packages install at user level. Microsoft MPI (MS-MPI) is the only supported MPI library.

As of LAMMPS version 17 February 2022, only 64-bit versions of the LAMMPS installer packages will be built and provided. If you must have a 32-bit version, you need to use an older version of LAMMPS or compile LAMMPS from source. Compiling LAMMPS on Windows with Visual Studio 2022 (available cost-free as Community Edition) is now fully supported.

As of LAMMPS version 27 May 2021, the LAMMPS installer packages will detect if LAMMPS (version 27 May 2021 or later) has already been installed and will offer to uninstall, in case it is. This should be independent from whether it was 32-bit or 64-bit version and with or without MPI or Python. Having multiple versions/variants of LAMMPS installed at the same time is no longer supported. Also, the name of the LAMMPS executable has been simplified to lmp.exe in all packages since there is no longer a need to differentiate between the MPI and non-MPI version.

Some Notes on GPU Support

These Windows binaries include GPU acceleration via the GPU package. This is achieved through compiling the GPU package in OpenCL mode and linking to an OpenCL compatible ICD loader. The included OpenCL loader library is compatible with OpenCL version 1.2 to 3.0. This means the executables do not contain any vendor provided code and should be compatible with current GPUs from AMD, Intel, and Nvidia. You need to have an HD or UHD GPU in an 8th generation or later core architecture Intel CPU for Intel GPU OpenCL support. Intel Xe type GPUs are not supported since they support single precision only. The GPU package has been compiled for mixed precision computation and as of LAMMPS version 10 March 2021 will automatically tune itself for the OpenCL capable hardware in use.

In the case of having multiple Vendor provided OpenCL runtimes installed, you may run into the situation of the "wrong" runtime being set as the default and used by LAMMPS. In this case, you may need to remove unwanted vendors from the windows registry database. Look for the key: HKEY_LOCAL_MACHINE\SOFTWARE\Khronos\OpenCL\Vendors, and remove vendors with non-functional OpenCL support. When reporting problems, please always include the exact version of the installer and the output of the ocl_get_devices tool.

LAMMPS Python module

These Windows binaries are built to include a shared library (liblammps.dll) and and also contain the LAMMPS Python wrapper module which is placed in a directory included in the PYTHONPATH environment variable. That makes it possible to import it into a suitable Python interpreter on Windows without any additional setup. This has been tested with the Python interpreters bundled with Microsoft Visual Studio and those downloaded from python.org but should be usable with any Python interpreter that is for the same architecture (32-bit or 64-bit x86).

This module is always included and the packages with a Python runtime include may import the LAMMPS python module from within their Python functions or classes. However, the LAMMPS installer packages do not include a Python executable for standalone use.

LAMMPS GUI

This is essentially a notepad like text editor for input files (with syntax highlighting for LAMMPS input) that is linked to the LAMMPS library so it can run LAMMPS inputs directly without a console window. The screen output from the simulation is captured and shown in a separate log window. After a run, it is also possible to create a snapshot image representing the current state of the simulation.

LAMMPS Shell

Installing LAMMPS on Windows

As of LAMMPS version 2 August 2023, the directory structure has been simplified and the number of package variants reduced.

The respective download directory will contain installer packages that are labeled with the date of the LAMMPS version and packages labeled as latest or stable. It is usually recommended to download and install a latest package to have the latest features and functionality. Installer packages for add-on plugins are also provided and follow a similar naming scheme. Download the installer executable suitable for your machine, execute it, and follow the instructions in the dialogs. Both kinds of packages contain:

The executables will run in serial when executed directly. Please see below for instructions on how to perform parallel runs.

MPI Support for LAMMPS on Windows

To use the MPI based parallelism in the provided installer packages, you also need to install Microsoft MPI (MS-MPI) that can be downloaded from the Microsoft home page. You only need to download and execute the msmpisetup.exe installer. This contains the runtime support. The additional download offered, msmpisdk.msi contains the files required to compile LAMMPS with MPI and Visual C++ from source code. If you would prefer to compile LAMMPS from source, you can follow the instructions in the LAMMPS manual for compiling LAMMPS with Visual Studio.

Older versions of LAMMPS binaries were compiled using a very old MPICH version from Argonne. As of the 2 August 20233 version, this is no longer supported.

Running LAMMPS on Windows

General Comments

LAMMPS is a text mode program, so you have to click on the Command Prompt entry in the windows start menu, launch the Windows Power Shell, or simply execute the command cmd from Start -> Run. The LAMMPS manual and the colvars reference manual in PDF format are linked from the start men, also references to open the file system browser to view the Benchmarks and Examples directory tree. The PATH environment variable is automatically set by the installer, so that the bundled executables from everywhere in the system. Also the LAMMPS_POTENTIALS environment variable is preset to the folder with the bundled manybody potential files, so they do not need to be copied into the respective working directory.

Serial Execution

To run a LAMMPS simulations please open a console window as outlined above and change to the directory with your input script and then run lmp as described in the LAMMPS manual. For more details and additional command line flags, please check out the LAMMPS Manual.

Multi-threaded Parallel Execution

All LAMMPS binaries from this repository support multi-threading via OpenMP, however by default only one thread is enabled. To enable more threads, e.g. four, you need to either set it at the command line prompt via set OMP_NUM_THREADS=4, via the -pk omp 4 command line flag, or via the package omp 4 command in your input script.

After enabling the use of multiple threads, you also have to select styles in LAMMPS, that are multi-thread enabled. Those are usually identified by the /omp suffix. Those can be selected explicitly and selectively, or with the suffix command or - most conveniently - via using the -sf omp command line flag to the LAMMPS executable.

Message Passing (MPI) Parallel Execution

Only the executable from the LAMMPS-MPI packages supports parallel execution via MPI (which can be combined with OpenMP multi-threading). For that you also need to install MS-MPI from Microssoft linked above.

MPI parallel executables have to be launched with mpiexec -localonly # lmp ... or mpiexec -np # lmp ... with "#" being then number of parallel processes to start.

Known Issues: while running in MPI parallel mode any output to the screen is block buffered and not line buffered as usual. That is, output will not show up immediately, but only after a certain amount of output has accumulated. This is done for efficiency reasons. Multi-threaded parallel or serial runs are not affected. Also when running under mpiexec, you should not use multi-threading, since MPICH restricts processes to a single physical CPU thus it will run less efficient.