Extensions

Due to its flexibility and modular nature, many extensions have been developed based on PySCF. As a courtesy, repositories for some of these extensions are hosted by the PySCF organization’s GitHub. However, the PySCF organization provides no support for these extensions, nor a guarantee of future compatibility. Questions should be addressed to the authors of the extension, and issues can be raised on the GitHub repository of the extension.

Once an extension module has been correctly installed (see How to install extensions), you can use it as a regular submodule of PySCF, e.g.,

import pyscf
from pyscf.semiempirical import MINDO3
mol = pyscf.M(atom='N 0 0 0; N 0 0 1')
MINDO3(mol).run()

A list of PySCF extensions is given below.

Project	URL
cas_ac0	https://github.com/CQCL/pyscf-ac0
cornell-shci	https://github.com/pyscf/cornell-shci
dftd3	https://github.com/pyscf/dftd3
dmrgscf	https://github.com/pyscf/dmrgscf
doci	https://github.com/pyscf/doci
fciqmc	https://github.com/pyscf/fciqmc
icmpspt	https://github.com/pyscf/icmpspt
mbd	https://github.com/pyscf/mbd
naive-hci	https://github.com/pyscf/naive-hci
nao	https://github.com/pyscf/nao
qsdopt	https://github.com/pyscf/qsdopt
rt	https://github.com/pyscf/rt
semiempirical	https://github.com/pyscf/semiempirical
shciscf	https://github.com/pyscf/shciscf
zquatev	https://github.com/sunqm/zquatev
tblis	https://github.com/pyscf/pyscf-tblis

How to install extensions

Many extension modules (e.g., the semiempirical module) can be installed using pip’s extra dependency mechanism,

pip install pyscf[semiempirical]

Although not recommended, all extension modules can be installed,

pip install pyscf[all]

How to install extensions (advanced)

Based on the technique of namespace packages specified in PEP 420, PySCF has developed a couple of methods to install the extension modules.

Pip command

For pip version newer than 19.0, projects hosted on GitHub can be installed on the command line,

pip install git+https://github.com/pyscf/semiempirical

A particular release on GitHub can be installed with the release URL you can look up on GitHub,

pip install https://github.com/pyscf/semiempirical/archive/v0.1.0.tar.gz

Pip command for local paths

If you wish to load an extension module developed in a local directory, you can use the local install mode of pip. Use of a Python virtual environment is recommended to avoid polluting the system default Python runtime environment, for example,

python -m venv /home/abc/pyscf-local-env
source /home/abc/pyscf-local-env/bin/activate
git clone https://github.com/pyscf/semiempirical /home/abc/semiempirical
pip install -e /home/abc/semiempirical

Environment variable PYSCF_EXT_PATH

You can place the location of each extension module (or a file that contains these locations) in this environment variable. The PySCF library will parse the paths defined in this environment variable, and load the relevant submodules. For example,

git clone https://github.com/pyscf/semiempirical /home/abc/semiempirical
git clone https://github.com/pyscf/doci /home/abc/doci
git clone https://github.com/pyscf/dftd3 /home/abc/dftd3
echo /home/abc/doci > /home/abc/.pyscf_ext_modules
echo /home/abc/dftd3 >> /home/abc/.pyscf_ext_modules
export PYSCF_EXT_PATH=/home/abc/semiempirical:/home/abc/.pyscf_ext_modules

Using this definition of PYSCF_EXT_PATH, the three extension submodules (semiempirical, doci, dftd3) are loaded when PySCF is imported, and you don’t have to use a Python virtual environment.