This code implements self-consistently the Perdew-Zunger self-interaction correction to approximate density functional calculations using orbitals taken from columns of the density matrix. Given a set of indices chosen from a pivoted QR decomposition of the density matrix, the energy is minimized using standard self-consistent iteration with an effective self-interaction multiplicative term added to the generalized Kohn-Sham Hamiltonian (just like in standard Kohn-Sham). The code is based on PYSCF.

The resulting localized orbitals are identical to those obtained with the SCDM-L method reported in

Selected Columns of the Density Matrix in an Atomic Orbital Basis I: An Intrinsic and Non-iterative Orbital Localization Scheme for the Occupied Space, E. G. Fuemmeler, A. Damle, R. A. J. DiStasio, J. Chem. Theory Comput. 2023, 19, 8572–8586.

Details will be published as

DOCSIC: A Mean-field, Orbital-by-orbital Method for Self-interaction Correction, J. E. Peralta, V. Barone, J. I. Melo, D. R. Alcoba, L. Lain, A. Torre, G. E. Massaccesi, and O. B. Oña.

Dependencies (developed and tested, but other versions might work):

• Python 3.11
• Numpy 1.25.0
• Scipy 1.11.2
• PySCF 2.5.0
• Torch 2.2.1

How to run the examples:

Methane:

python3.11 example_1.py methane

Water (with maximum overlap method):

python3.11 example_2.py

Ethylene+:

python3.11 example_3.py

Generate cube files:

python3.11 example_3.py isobutene