[Wannier] Al Chain

[Jonathan Yates]

On 23 Jan 2010, at 12:11, Jonathan Yates wrote:

>
> On 23 Jan 2010, at 11:40, Mohammad Saghayezhian wrote:
>
>> We have a problem with constructing well-localized wannier functions
>> for Al chain, According to (ab initio transport properties of
>> nanostructures from maximally localized wannier functions) PRB
>> 69,035108 (Calzolari et al), we followed the steps one by one, we
>> took the same vacuum, lattice parameter, kpoints, and everything,
>> but the wanniers are not localized and the ratio of Im/Re is rather
>> large,

[Mohammad sent his input files to me directly]

Mohammad,

  From your input files I see you are trying to extract 8 wannier  
functions from a set of 15 bands.
If you take a slightly larger set of bands (say 20) - you will find  
that the disentanglement stage converges quickly - and the final WF  
are well localised.

  To understand this look at the band-structure plot in Fig 2 of PRB  
69 035108. The set of 8 MLWF have a particular set of symmetry  
characteristics - the disentanglement routine is selecting the  
appropriate set of bloch states to capture this symmetry. At Gamma the  
routine chooses a state with quite high energy, neglecting several  
states with lower energy (but presumably with different symmetry).  
This state lies above the 15th band - hence why you initially had  
problems.

  Jonathan



-- 
Department of Materials, University of Oxford, Parks Road, Oxford, OX1  
3PH, UK
tel: +44 (0)1865 612797                http://users.ox.ac.uk/~oums0549/