LibXC GGA & MetaGGA in the vaccuum
Summary
LibXC should also support the vaccum for GGAs and MetaGGAs
Why is this feature needed?
It seems most FLEUR users are doing somekind of Film calculations.
Implementation ideas
I am not sure how much effort we should invest. The easiest would be to say that the vaccuum only has a small contribution to the total energy and that we therefore can do LDA/GGA in the vacuum, but this seems very hacky.
Any opinions on this?