[Wannier] Wannier functions of molecular crystal

[Jonathan Yates]

On 14 Apr 2010, at 13:39, Gianluca Giovannetti wrote:

> Dear Jonathan,
> 
> thank you for the reply.
> 
> I think i have still some troubles to understand how to give a good starting guess. :-)
> 
> Please let look at this paper:
> 
> J. Phys. Soc. Jpn. 78 (2009) 113704 
> 
> and let think we want to reproduce exactly the WFs in their Fig. 3.
> 
> As you can see the Wannier functions are localized over all the molecule and they look like some linear combination of p states over all the C and H ions.

Those WF are quite extended - which is not so surprising given the Bloch states they correspond to.

 I admit I am not sure what the best projection would be. Experiment! (maybe pick an atom in the middle and but a pz on it?). Remember the projection is just a starting guess - it should not be too critical. Maybe run the wannierisation for a large number of steps.
 As your cell is quite large you might try gamma point and the gamma only routines, the bandstructure won't be good - but the MLFW might have the same form as for better kpoint samplings. Gamma point is the most robust minimisation scheme (it is a much simpler problem)


> Is the option " f=0,0.50,0:pz" a good starting guess?
> Is the latter option the best i can use in such case?

 No - it was just an example to demonstrate the syntax, nothing to do with your system.

 Jonathan


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