[Wannier] Req. uniqueness of Maximally localized Wannier functions

[Soumyadeep]

Thank you very much professor Marzari for an elaborate description. But 
for MLWF, I check only these

(1) DFT and wannier interpolated band structure must match in inner 
energy window
(2) final spread is low
(3) Img[h^R_ij] ~ 0

Is there any other factor I need to check?

Normally I work on Fe-based superconducting materials which is metallic 
in nature and also have entangled bands.

with best regards
Soumyadeep


On 09-03-2020 16:54, Nicola Marzari wrote:
> Hi Soumyadeep,
> 
> plenty of literature on this, but some cases are discussed in Sec III 
> of
> https://arxiv.org/abs/1909.00433
> 
> In a nutshell: for non-magnetic insulators, the localization
> functional on the occupied bands seems to have one (or multiple, by
> symmetries - think benzene) well defined global minimum - all others
> correspond to messed-up phase factors, give rise to meaningless WFs,
> and those are not real (i.e. they have an imaginary components). I
> cannot discount though that e.g. during a mol. dyn. simulations one
> could find discontinuous jumps in the MLWFs centers from one timestep
> to another.
> 
> For non-magnetic systems where you disentangle also the empty bands,
> you can have more subtle, complex effects (see discussion above). In
> that respect, it also dependes if we call maximally localized the
> global minimum only, or also other local minima where WFs are real and
> look meaningful.
> 
> For magnetic system, we have less case studies, and in general there
> are already multiple local minima of the KS-DFT functional.
> 
> If anyone has experiences something different, welcome to mention it 
> here.
> 
> 				nicola
> 
> 
> On 09/03/2020 06:21, Soumyadeep wrote:
>> Dear All,
>> 
>>    I have a query, is Maximally localized Wannier functions are unique 
>> set of functions? I mean for a particular system only one set of MLWF 
>> is possible or it can be many set depending on other factors?
>> 
>>    Waiting eagerly for your reply.
>> 
>> with many thanks and best regards
>> Soumyadeep
>> -------------------------------------------------------------------
>> Soumyadeep Ghosh,
>> Senior Research Fellow,
>> Homi Bhabha National Institute (HBNI),
>> Raja Ramanna Centre for Advanced Technology, Indore, India-452013
>> Mob: (+91)9424664553
>> User Lab: 0731244-2580
>> Email: soumyadeepghosh35 at gmail.com, soumyadeep at rrcat.gov.in
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