[Wannier] Preparation of the projections block

[Jonathan Yates]

On 2 Aug 2010, at 21:53, Jian-Xin Zhu wrote:

> Dear Jonathan and Respectful Wannier Users,
> 
> When I prepare the projections block in the case.win file, a question arises ---
> 
> If I have a 2 types of Vanadium atoms in the unit cell for ab-inition calculations and each type has 4 equivalent V atoms,
> how many lines should I put in the 
> Begin Projections 
> ...
> End Projections
> block? 
> 
> From the Wannier90: User Guide, I read on page 34 "C, Al etc. applies to all atoms of that type". 
> So I understand I should put in 2 lines since there are two types of Vanadium. As such, I prepare the 
> projections block as follows: 
> 
> Begin Projections 
> V: l=0;l=1;l=2
> V: l=0;l=1;l=2
> End Projections


Jianxin,

That's not quite correct. 

Wannier90 doesn't know anything about the symmetry equivalence of the atoms.

So if you put

Begin Projections 
V: l=0;l=1;l=2
End Projections

you will get s,p,d projections on each Vanadium atom in your system (ie all 8 in your example).
If this is what you want, this is sufficient.


You might have a situation where you do want different projections for the inequivalent V (maybe if you had an antiferromagnetic system). In which case you could do something like

Begin atoms_cart
V1 0.00 0.00 0.00
V1 0.00 0.00 0.50
V2 0.25 0.25 0.25
V2 0.25 0.25 0.75
end atoms_cart

Begin Projections 
V1: l=0;l=1;l=2
End Projections

which puts projections on only half of the V.

Yours
Jonathan

(ps. apologies for the repeated email - I forgot to send it to the list the first time)




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