Martin Lueders requested to merge fxc-gga into develop Jan 07, 2020

Description

This MR implements the f_xc kernel for GGA functionals. Currently, GGA + spinors are still excluded.

News snippet

This MR implements f_xc for GGA functionals.

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.