[Wannier] Gamma-point setting

[Stefan Badescu]

Dear users,

I thought it may be of some interest to mention this Gamma-point 
calculations. Maybe this was signaled before on this forum.

I found that using 'gamma_only = .true.' does not always converge for 
large systems. It may go past the disentaglement but in the 
wannierisation step it gives pretty large spreads and may not converge. 
If I use the default 'gamma_only = .false.' I avoid this problem most of 
the time, even if it somewhat slower. It also gives smaller spreads in 
the first step - disentanglement.

The examples I used for this are graphene substrates with up to 288 C 
atoms, on which I have somewhere between 6 to 36 chemisorbed atoms.

--Stefan