[Wannier] Req. uniqueness of Maximally localized Wannier functions

[Nicola Marzari]

Looks good to me, and in outer you want the wannier interpolated to be 
smooth.

			nicola


On 09/03/2020 15:04, Soumyadeep wrote:
> 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
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>>> Email: soumyadeepghosh35 at gmail.com, soumyadeep at rrcat.gov.in
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-- 
----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
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