Using LAMMPS–GUI

Note

For simplicity, these tutorials reference keyboard shortcuts based on the assignments for Linux and Windows. macOS users should use the Command key in place of the Ctrl key when using keyboard shortcuts.

Installation

Precompiled versions of LAMMPS–GUI are available for Linux, macOS, and Windows on the LAMMPS GitHub Release page. The Linux version is provided in two formats: as compressed tar archive (.tar.gz) and as a Flatpak bundle. The macOS version is distributed as a .dmg installer image, while the Windows version comes as an executable installer package.

Installing the Linux .tar.gz Package

Download the archive (e.g., LAMMPS-Linux-x86_64-GUI-29Aug2024_update2.tar.gz) and unpack it. This will create a folder named LAMMPS–GUI containing the included commands, which can be launched directly using ./lammps-gui or ./lmp, for example. Adding this folder to the PATH environment variable will make these commands accessible from everywhere, without the need for the ./ prefix.

Installing the Linux Flatpak Bundle

You have to have Flatpak support installed on Linux machine to be able to use the Flatpak bundle. Download the bundle file (e.g., LAMMPS-Linux-x86_64-GUI-29Aug2024_update2.flatpak) and then install it using the following command:

flatpak install --user LAMMPS-Linux-x86_64-GUI-29Aug2024_update2.flatpak

This will integrate LAMMPS–GUI into your desktop environment (e.g., GNOME, KDE, XFCE) where it should appear in the Applications menu under Science. Additionally, the .lmp file extension will be registered to launch LAMMPS–GUI when opening a file with this extension in the desktop’s file manager.

You can also launch LAMMPS–GUI from the command-line using the following command:

flatpak run org.lammps.lammps-gui

Similarly, for launching the LAMMPS command-line executable, use:

flatpak run --command=lmp org.lammps.lammps-gui -in in.lmp

Installing the macOS Application Bundle

After downloading the macOS app bundle image file (e.g., LAMMPS-macOS-multiarch-GUI-29Aug2024_update2.dmg), double-click on it. In the dialog that opens drag the LAMMPS–GUI app bundle into the Applications folder. To enable command-line access, follow the instructions in the README.txt file. These macOS app-bundles contain native executables for both, Intel and Apple CPUs.

After installation, you can launch LAMMPS–GUI from the Applications folder. Additionally, you can drag an input file onto the app or open files with the .lmp extension. Note that the LAMMPS–GUI app bundle is currently not cryptographically signed, so macOS may initially prevent it from launching. If this happens, you need to adjust the settings in the Security & Privacy system preferences dialog to allow access.

Installing the Windows package

Download the LAMMPS–GUI installer for Windows (e.g., LAMMPS-Win10-64bit-GUI-29Aug2024_update2.exe). Windows may warn you that the file is from an unknown developer and was downloaded from the internet. This happens because neither the installer nor the LAMMPS–GUI application (or any other included applications) have been cryptographically signed. You will need to choose to keep the file, and when launching the installer, confirm that you want to run it despite the warning.

After installation, a new entry should appear in the Start menu. Additionally, the .lmp file extension should be registered with Windows File Explorer to open LAMMPS–GUI when opening a file with the .lmp extension. The lammps-gui and lmp commands should also be available in the command-line.

Opening, Editing, and Saving Files

LAMMPS–GUI can be launched from the command-line, as explained above, where you can either launch it without arguments or provide one file name as an argument. All other arguments will be ignored. For example:

lammps-gui input.lmp

Files can also be opened from the File menu. You can select a file through a dialog and then open it. Additionally, a history of the last five opened files is maintained, with entries to open them directly. Finally, the Ctrl-O keyboard shortcut can also be used to open a file.

When integrated into a desktop environment, it is also possible to open files with a .lmp extension or use drag-and-drop.

For the most part, the editor window behaves like other graphical editors. You can enter, delete, or copy and paste text. When entering text, a pop-up window will appear with possible completions after typing the first two characters of the first word in a line. You can navigate the highlighted options using the up and down arrow keys, and select a completion by pressing the Enter key or using the mouse. You can also continue typing, and the selection in the pop-up will be refined. For some commands, there will be completion pop-ups for their keywords or when a filename is expected, in which case, the pop-up will list files in the current folder.

As soon as LAMMPS–GUI recognizes a command, it applies syntax highlighting according to built-in categories. This can help detect typos, since those may cause LAMMPS–GUI not to recognize the syntax and thus not apply or partially apply the syntax highlighting. When you press the Tab key, the line will be reformatted. Consistent formatting can improve the readability of input files, especially long and complex ones.

If the file in the editor has unsaved changes, the word modified will appear in the window title. The current input buffer can be saved by selecting Save or Save As... from the File menu. You can also click the Save icon on the left side of the status bar, or use the Ctrl-S keyboard shortcut.

Note

When LAMMMPS–GUI opens a file, it will switch the working directory to the folder that contains the input file. The same happens when saving to a different folder than the current working directory. The current working directory can be seen in the status bar at the bottom right. This is important to note because LAMMPS input files often require additional files for reading and may write output files (such as images, trajectory dumps, or averaged data files), which are typically expected to be in the same folder as the input file.