LAMMPS Documentation (30 Jul 2021 version)

LAMMPS stands for Large-scale Atomic/Molecular Massively Parallel Simulator.

LAMMPS is a classical molecular dynamics simulation code with a focus on materials modeling. It was designed to run efficiently on parallel computers. It was developed originally at Sandia National Laboratories, a US Department of Energy facility. The majority of funding for LAMMPS has come from the US Department of Energy (DOE). LAMMPS is an open-source code, distributed freely under the terms of the GNU Public License Version 2 (GPLv2).

The LAMMPS website has a variety of information about the code. It includes links to an on-line version of this manual, a mailing list and online forum where users can post questions, and a GitHub site where all LAMMPS development is coordinated.

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The content for this manual is part of the LAMMPS distribution. The online version always corresponds to the latest development version. If needed, you can download or build a local copy of the manual as HTML pages or a PDF file by following the steps on the Build the LAMMPS documentation page. If you have difficulties viewing the pages please see this note.

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The manual is organized in three parts: 1) the User Guide for how to install and use LAMMPS, 2) the Programmer Guide for how to write programs using the LAMMPS library from different programming languages and how to modify and extend LAMMPS, and 3) the Command Reference which includes detailed descriptions of all commands included in the LAMMPS code.

Once you are familiar with LAMMPS, you may want to bookmark this page since it gives quick access the documentation for all LAMMPS commands.

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User Guide

User Guide

• 1. Introduction
  • 1.1. Overview of LAMMPS
  • 1.2. What does a LAMMPS version mean
  • 1.3. LAMMPS features
  • 1.4. LAMMPS non-features
  • 1.5. LAMMPS open-source license
  • 1.6. Authors of LAMMPS
  • 1.7. Citing LAMMPS
  • 1.8. Additional website links
• 2. Install LAMMPS
  • 2.1. Download an executable for Linux
  • 2.2. Download an executable for Mac
  • 2.3. Download an executable for Windows
  • 2.4. Download an executable for Linux or Mac via Conda
  • 2.5. Download source and documentation as a tarball
  • 2.6. Download the LAMMPS source with git
• 3. Build LAMMPS
  • 3.1. Build LAMMPS with CMake
  • 3.2. Build LAMMPS with make
  • 3.3. Link LAMMPS as a library to another code
  • 3.4. Basic build options
  • 3.5. Optional build settings
  • 3.6. Include packages in build
  • 3.7. Packages with extra build options
  • 3.8. Build the LAMMPS documentation
  • 3.9. Notes for building LAMMPS on Windows
  • 3.10. Notes for saving disk space when building LAMMPS from source
  • 3.11. Development build options
• 4. Run LAMMPS
  • 4.1. Basics of running LAMMPS
  • 4.2. Command-line options
  • 4.3. Screen and logfile output
  • 4.4. Running LAMMPS on Windows
• 5. Commands
  • 5.1. LAMMPS input scripts
  • 5.2. Parsing rules for input scripts
  • 5.3. Input script structure
  • 5.4. Commands by category
  • 5.5. General commands
  • 5.6. Fix commands
  • 5.7. Compute commands
  • 5.8. Pair_style potentials
  • 5.9. Bond_style potentials
  • 5.10. Angle_style potentials
  • 5.11. Dihedral_style potentials
  • 5.12. Improper_style potentials
  • 5.13. KSpace solvers
  • 5.14. Removed commands and packages
• 6. Optional packages
  • 6.1. Available Packages
  • 6.2. Package details
• 7. Accelerate performance
  • 7.1. Benchmarks
  • 7.2. Measuring performance
  • 7.3. General tips
  • 7.4. Accelerator packages
  • 7.5. Comparison of various accelerator packages
• 8. Howto discussions
  • 8.1. General howto
  • 8.2. Settings howto
  • 8.3. Analysis howto
  • 8.4. Force fields howto
  • 8.5. Packages howto
  • 8.6. Tutorials howto
• 9. Example scripts
  • 9.1. Lowercase directories
  • 9.2. Uppercase directories
• 10. Auxiliary tools
  • 10.1. Pre-processing tools
  • 10.2. Post-processing tools
  • 10.3. Miscellaneous tools
  • 10.4. Tool descriptions
• 11. Errors
  • 11.1. Common problems
  • 11.2. Reporting bugs
  • 11.3. Debugging crashes
  • 11.4. Error messages
  • 11.5. Warning messages

Programmer Guide

Programmer Guide

• 1. LAMMPS Library Interfaces
  • 1.1. LAMMPS C Library API
  • 1.2. LAMMPS Python APIs
  • 1.3. LAMMPS Fortran API
  • 1.4. LAMMPS C++ API
• 2. Use Python with LAMMPS
  • 2.1. Overview
  • 2.2. Installation
  • 2.3. Run LAMMPS from Python
  • 2.4. The lammps Python module
  • 2.5. Extending the Python interface
  • 2.6. Calling Python from LAMMPS
  • 2.7. Output Readers
  • 2.8. Example Python scripts
  • 2.9. Handling LAMMPS errors
  • 2.10. Troubleshooting
• 3. Modifying & extending LAMMPS
  • 3.1. Overview
  • 3.2. Submitting new features for inclusion in LAMMPS
  • 3.3. Atom styles
  • 3.4. Pair styles
  • 3.5. Bond, angle, dihedral, improper styles
  • 3.6. Compute styles
  • 3.7. Fix styles
  • 3.8. Input script command style
  • 3.9. Dump styles
  • 3.10. Kspace styles
  • 3.11. Minimization styles
  • 3.12. Region styles
  • 3.13. Body styles
  • 3.14. Thermodynamic output options
  • 3.15. Variable options
• 4. Information for Developers
  • 4.1. Source files
  • 4.2. Class topology
  • 4.3. How a timestep works
  • 4.4. Writing new styles
  • 4.5. Notes for developers and code maintainers
  • 4.6. Writing plugins
  • 4.7. Adding tests for unit testing
  • 4.8. C++ base classes
  • 4.9. Utility functions
  • 4.10. Tokenizer classes
  • 4.11. Argument parsing classes
  • 4.12. File reader classes
  • 4.13. Memory pool classes
  • 4.14. Eigensolver functions
  • 4.15. Communication buffer coding with ubuf

Command Reference

Command Reference

• Commands
• Fixes
• Computes
• Pair Styles
• Bond Styles
• Angle Styles
• Dihedral Styles
• Improper Styles
• fix_modify AtC commands
• Bibliography

Indices and tables

• Index

• Search Page

Web Browser Compatibility

The HTML version of the manual makes use of advanced features present in “modern” web browsers. This can lead to incompatibilities with older web browsers (released more than 4 years ago) and specific vendor browsers (e.g. Internet Explorer on Windows; Microsoft Edge works well though) where parts of the pages are not rendered as expected (e.g. the layout is broken or mathematical expressions not typeset). In that case we recommend to install/use a different/newer web browser or use the PDF version of the manual.