map%rank_list(1) = coord2rank_cfd(pcoords(1),pcoords(2),pcoords(3))
Store the minimum and maximum CFD cell coordinates that overlap each MD processor.
Store MD processor coordinates that overlap each CFD processor coordinate.
@author David Trevelyan Splits the world communicator into "overlap" communicators. Each overlap communicator consists of a CFD root processor and the MD processors which lie on top of it in the domain.