Installation

Step 0: Setup a Python Virtual Environment

FriendZone interacts with its friends through Python. We thus highly recommend (and this tutorial will assume) that you setup a Python virtual environment prior to installing anything. This is done by:

python -m venv my_venv
source my_venv/bin/activate

Here my_venv is the name of the virtual environment you are creating (feel free to change this). The above commands will create a virtual environment my_venv which lives in the directory you run the commands in (Python virtual environments are simply directories) and activate it (which makes that the Python installation used until the environment is deactivated, which is done by running the appropriately named command deactivate).

Step 1: Install FriendZone Dependencies

FriendZone depends on SimDE, several Python modules, and whatever friends (i.e., other electronic structure packages) you want to enable. FriendZone’s build system can build and install SimDE for you (if it is not found), but at present it can not install the Python modules or friends.

To install the Python module dependencies into the virtual environment from Step 0 (so assuming it is still activated) simply run the following in the root directory of FriendZone:

pip install -r requirements.txt

The installation instructions for each friend can vary widely and we have dedicated the entire How to Install Our Various Friends section below to this topic.

Step 2: Install FriendZone

Once the dependencies are installed, FriendZone can be built using the usual CMake commands:

cmake -H. \
      -B<build_dir> \
      -DCMAKE_INSTALL_PREFIX:PATH=<where/to/install/libraries> \
      -DCMAKE_TOOLCHAIN_FILE:PATH=<path/to/toolchain.cmake>
cmake --build build --target install --parallel 2

Here <build_dir> is the name of the build directory CMake should use (most users just set this to -Bbuild), <where/to/install/libraries> should be set to where you want to install the dependencies FriendZone builds for you, and <path/to/toolchain.cmake> should point to your toolchain.cmake file. Of particular note, make sure that in your toolchain file you set NWX_MODULE_PATH to where you want FriendZone installed and you may want to set both Python_EXECUTABLE and Python3_EXECUTABLE to the Python interpreter from your virtual environment (with the environment activated run which python3 to get it’s path).

Step 3: Play Nicely with Friends

Once FriendZone is installed you should be able to just include NWX_MODULE_PATH in your PYTHONPATH and be able to use it!

How to Install Our Various Friends

NWChem

Full instructions can be found here.

The easiest way to install NWChem (although such an installation is unlikely to be high-performance) is via a package manager. On Ubuntu/Debian, this is simply:

sudo apt-get install nwchem

For Mac, NWChem can be installed via [Homebrew](https://brew.sh/):

brew install nwchem

For performance critical runs, it is strongly recommended that you build NWChem from source.