How to install MolTwister

Obtaining MolTwister

The first step is to download MolTwister. Goto the MolTwister homepage and select Download. You will be directed to the GitHub repository of MolTwister. The download can be done in two ways

  1. Perform a git clone of the repository

  2. Download the zip file of the repository


Depending on the method used to download MolTwister, it may be necessary to install Git. On Ubuntu this is done by

sudo apt install git

On MacOS, Git can be installed using binary installers or through repositories, such as Homebrew. For example,

brew install git

GCC, G++ and CLang

MolTwister is written in C++. Hence, if GCC and G++ has not been installed, they must be installed. On Ubuntu, this can be done by

sudo apt install gcc
sudo apt install g++

On MacOS, MolTwister will be compiled using CLang. If CLang is not installed. make sure it is installed. This can be done by installing XCode.


To compile MolTwister, version 3.11, or greater, of CMake must be installed. On ubuntu, this can be done by

sudo apt install cmake

It is also possible to simplify the compilation process by installing cmake-gui:

sudo apt install cmake-gui

The GNU Readline Library

MolTwister uses the GNU Readline Library. The source code and binary files, in addition to installation instructions, are available at The GNU Readline Library home page. However, it is also possible (e.g., on Ubuntu) to install the development version through a repository:

sudo apt install libreadline-dev

The library is also avialable on repositories for MacOS and can be installed using Homebrew or MacPorts. For example,

brew install readline


Python/C comes with Python and is used by MolTwister. On Ubuntu, this can be installed by

sudo apt install python3
sudo apt install libpython3-dev

Note that the Python3 package usually comes pre-installed on newer versions of Ubuntu. For MacOS, the Python3 package can be downloaded from It may also be necessary to install XCode to obtain the appropriate development libraries to compile Python/C specific code.


MolTwister uses OpenGL. Hence, the OpenGL development packages must be installed. On Ubuntu, this can be done by

sudo apt install libopengl-dev
sudo apt-get install libglu1-mesa-dev freeglut3-dev mesa-common-dev

If XCode is installed on MacOS, then development libraries for both OpenGL and the GLUT libraries should already be installed.

Compiling MolTwister

To compile MolTwister from the command line, goto the MolTwister source folder (where the CMakeLists.txt file resides). Then, type



To compile with GPU acceleration for the MD simulator in MolTwister, the latest CUDA development toolkit must be installed, together with appropriate drivers for the graphics card. To compile with cuda, use


There also exists a command line switch to enable debug code. This is achieved by adding


to the cmake call above.

Using QtCreator

It is recommended to use QtCreator as an IDE for the MolTwister project (since this has been tested extensively, both on MacOS and Ubuntu). The project is opened by choosing “Open Project” and selecting the CMakeLists.txt file. The first time the project is opened, the IDE will ask to configure the project. In that case, select “Desktop Qt x.y.z …” (for MacOS choose the clang 64bit compiler). A file called CMakeLists.txt.user will be created. If it becomes necessary to redo the configuration process, simply delete this file. To perform the cmake configuration right click the project and select “Run CMake” (usually happend automatically the first time the project is configured). After this, it is possible to right click and select “Build” or “Rebuild”.

On the menu that by default appears at the left hand side of the IDE window, there are a few options (”Welcome”, “Edit”, “Debug”, “Projects” and “Help”). Click on “Projects” and “Build” (under “Build & Run”). There, it is possible to select and deselect the INCLUDE_CUDA_COMMANDS and CUDA_DBG_INFO options. Activate the selection by clicking “Apply Configuration Changes”. Then, “Run CMake” and “Rebuild”.

On MacOS, it is important to goto Projects > Buid & Run > Run, from the left hand menu bar and tick “Run in Terminal”.

Installation of MolTwister

If MolTwister was compiled from the command line, make sure the working folder is the folder containing the source code (same folder as pulled from Git and the same folder from where make was called). In case QtCreater was used to build MolTwister, goto the build output folder created by QtCreator. Usually, the output folder is created one level below the source folder. However, this is configurable through the QtCreator user interface. Then execute

sudo make install

This will install MolTwister as ‘moltwister’ under /usr/local/bin.

It should now be possible to execute the moltwister command from any folder from within the command prompt, to start MolTwister.