Nicolas Tancogne-Dejean requested to merge rmmdiis_debug_fix into develop Apr 07, 2022

Description

Fix different problems with the RMMDIIS algorithm.

The lowest eigenvalue is now found from solving the full generalized eigenvalue problem, as the other approach could lead to minus the eigenvector.
The backup treatment for non-positive overlap matrices is now extended to complex wavefunctions
The value of lambda is now computed in a safer way, and the allowed range is increased up to 1000

News snippet

Major improvement of the RMMDIIS algorithm by fixing some bugs and improving other aspects.

Checklist

I have checked that my code follows the Octopus coding standards
I have added tests for all the new features added in this request.