Dispersion

[ajhoffman1229]

Summary

Major changes:

• tutorial: added a python notebook tutorial showing users how to add a dispersion correction to the main CHGNet model. Approving this would address [Feature Request]: Add dispersion to ASE calculator #188 .

Checklist

This PR would not add any new features to the core code and only contains a notebook showing how to add dispersion to the CHGNet calculator through ASE. I installed pre-commit hooks and used them to format the code in the notebook.

• All existing tests pass.
• Tests have been added for any new features/fixes.
• Docstrings have been added in the Google docstring format.

[janosh]

after pip install torch_dftd dftd4, examples/dispersion.ipynb doesn't run for me. getting a kernel crash from the import cell:

[ajhoffman1229]

I am not sure that DFT-D4 has a module available on pypi, you may need to use conda or mamba. Can you also install the python extension of DFT-D4? I think you will need conda install dftd4 dftd4-python -c conda-forge per the instructions here. I remember having a similar issue before when I installed the base dftd4 package without the dftd4-python component and tried to import DFT-D4. Without the python part, the import will fail.

Also, did you run pip install torch_dftd or pip install torch-dftd? I believe the latter is what is listed on pypi and I'm not sure the installation will work with an underscore.

[janosh]

I am not sure that DFT-D4 has a module available on pypi, you may need to use conda or mamba.

i see. not a fan of conda or mamba (strongly prefer uv). but that's not a PR blocker ofc, esp. for an optional dep. @BowenD-UCB you wanna try running the notebook? else happy to merge as is.

PS: pip install torch-dftd and pip install torch_dftd are equivalent.

[ajhoffman1229]

I am not sure that DFT-D4 has a module available on pypi, you may need to use conda or mamba.

i see. not a fan of conda or mamba (strongly prefer uv). but that's not a blocker PR ofc, esp. for an optional dep. @BowenD-UCB you wanna try running the notebook? else happy to merge as is.

PS: pip install torch-dftd and pip install torch_dftd are equivalent.

I had not heard of uv before but I can understand the appeal, thank you for sharing! I like the idea of a rust-based environment manager.

[BowenD-UCB]

Hi @ajhoffman1229 and @janosh
Thanks for the PR!
Sorry for the delay on this.
I tried to install these extra dependencies but encountered installation issue (package incompatibilities) with dftd4-python
As these are optional deps I'll merge as it is now.