Fixed

• Ensure {autolink}~meanfi.params.rparams.tb_to_rparams and {autolink}~meanfi.params.rparams.rparams_to_tb use minimal parametrisation of the tight-binding dictionary.

Added

• Density matrix cost for the mean-field solver.
• Functionality {autolink}~meanfi.kwant_helper.utils.tb_to_builder to create kwant systems with the tight-binding dictionaries.
• Functionality {autolink}~meanfi.kwant_helper.utils.tb_to_kfunc to create k-dependent function from tight-binding format.

Changed

• Rewrote {autolink}~meanfi.kwant_helper.utils.builder_to_tb to avoid potential bugs and remove the use of copy.