New version 1.1

A lot of bugs have been solved, and finally, we release the stable version of the python-sscha code.

The focus of this release was to improve the user experience. To this aim, we implemented a better minimization algorithm and a much improved variable cell relaxation algorithm. In particular, we:

1. Minimization now occurs with automatic step selection (line-minimization), able to account also for imaginary frequencies and too drastic steps due to the stochastic nature of the algorithm. The user does not have to specify the step anymore, as the automatic step selection works extremely well.
2. The variable cell minimization algorithm uses a similar line-minimization approach, we also fixed a bug in the units of the bulk modulus. Now the algorithm for the cell dynamics is robust and never diverges, even with a noisy ensemble.
3. Speedup of the code. We removed a lot of redundant diagonalization performed throughout the code that slowed down the minimization, in particular for systems with a large primitive cell.

We have also added some useful extra features to the ensemble class, like the possibility to save into the raw format to interface with DeepMD-kit code (you can use your SSCHA ensemble to train a neural network potential!)

Furthermore, we extended the functionality of cluster calculation, which is more stable. Still, a major update on the cluster interface will come in the near future.

Remember to upload also CellConstructor to version 1.1, as the two codes must always work in paired versions.

What's Changed

• Implement v4 by @mesonepigreco in #9
• Dynamical supercell by @mesonepigreco in #10
• Update the automatic test on the master inside EasyFixModes branch by @mesonepigreco in #26
• Spectral tutorial by @rafbianco in #30
• Compare the advances on the MPI with respect to the master by @mesonepigreco in #12
• Put EasyFixModes update by @mesonepigreco in #32
• Easy fix modes by @mesonepigreco in #29
• Fix the import error and updated the version to match the pip release by @mesonepigreco in #36
• Line minimization by @mesonepigreco in #47
• Fast wpols by @mesonepigreco in #54
• New cluster interface by @mesonepigreco in #61
• Added a new way to compute the energy and forces using calculators wi… by @mesonepigreco in #62

New Contributors

• @rafbianco made their first contribution in #30

Full Changelog: https://github.com/SSCHAcode/python-sscha/commits/v1.1