How to install NWChemEx

NWChemEx is a modular software package that can be extended with plugins. Here we are focused on the user install, which will provide you with the core NWChemEx package. With such an install you can load and use additional plugins. If you are interested in developing your own plugins/modules see the developer install instructions.

Install NWChemEx from a package manager

TODO: Write me!

Build NWChemEx from source

At present we only officially support building NWChemEx on Linux, or Mac. We know that several developers have also built it on Windows using the Windows Linux Subsystem; however, we do not officially support this.

This tutorial assumes familiarity with the terminal.

Step 1: Obtain build tools and dependencies

NWChemEx can build most of its dependencies automatically. The ones it cannot build are commonly available packages. If you need help installing dependencies visit Installing NWChemEx dependencies.

Step 2: Obtain the source code

Navigate to the directory where you want to download the NWChemEx source code, for example:

cd /Users/my_username/

will cause the next command to download the source code into the directory /Users/my_username/NWChemEx (the next command will automatically create the NWChemEx subdirectory).

Clone the NWChemEx GitHub repository:

git clone https://github.com/NWChemEx/NWChemEx.git

Step 3: (Recommended) Install with pip

We advocate for the use of Python virtual environments to avoid contaminating your system Python installation. The following snippet will create a virtual environment in the newly created NWChemEx directory and then install NWChemEx to the virtual environment.

cd NWChemEx
python -m venv .venv
source .venv/bin/activate
pip install .

Step3: (Alternative) Install with CMake

The pip install is a thin wrapper over a CMake build. If you’d prefer a more “standard” C++ experience you can also build NWChemEx with CMake via:

cd NWChemEx
cmake -B build -H. -GNinja -DCMAKE_INSTALL_PREFIX=./install 
cmake --build build --parallel

Some notes:

• This will install NWChemEx into a directory install/ located in the NWChemEx/ directory. Change the location if you would prefer it be installed elsewhere. We strongly suggest specifying a local path and NOT letting CMake install it system-wide (the default if CMAKE_INSTALL_PREFIX is not set).
• -GNinja tells CMake to use the Ninja build system, which is much faster than the default. It does however, require Ninja to be pre-installed (See Installing NWChemEx dependencies for instructions). You can omit the -GNinja flag if you do not want to install Ninja.