[Wannier] Wien2k2Wannier90

[Jonathan Yates]

On Fri, 19 Sep 2008, fatemeh.mirjani wrote:

> if the spread becomes negative what does it mean?
> I found some mistakes in my code so I edited it . but I haven't  succeed to get correct WFs yet.
> the flactuations in the bandstructure decreased but it is still wrong !
> the spread becomes negative:
> Final State
>  WF centre and spread    1  ( -1.171555,  0.170504, -0.083959 )  -380.61012680
>  WF centre and spread    2  (  1.200799, -1.606712, -0.120351 )   -20.08399486
>  WF centre and spread    3  (  0.126184,  0.772680,  2.072708 )  -384.87801891
>  WF centre and spread    4  (  0.879826,  1.219855, -0.570418 )   -26.25860467
>  Sum of centres and spreads (  1.035253,  0.556326,  1.297980 )  -811.83074525
>
>        Spreads (Bohr^2)       Omega I      = -1298.918567808
>        ================       Omega D      =   213.863027239
>                               Omega OD     =   273.224795323
>   Final Spread (Bohr^2)       Omega Total  =  -811.830745246
>
> I know the omega & omega I & D should be positive. In this calculation 
> only omega I is negative (Also the amoun of other omega aren't 
> reasonable). With regard to the fact that omega I is invarient does it 
> mean the projection is wrong?

For an isolated group of bands Omega_I is determined only from the data 
contained in the *.mmn file - so you can ignore the projections and focus 
on getting the Mmn matrix computed correctly.

  A simpler test case, which I've found useful in the past, is to consider 
just the lower valence band of GaAs. This gives an s-like WF centred on 
the As atom (see Table III of MV for representative values of the spread)

  Jonathan


-- 
Dr Jonathan Yates         |    Theory of Condensed Matter Group
Corpus Christi College    |    Cavendish Laboratory
Cambridge, CB2 1RH, UK    |    Cambridge, CB3 OHE, UK
email jry20 at cam.ac.uk     |    Tel +44 (0)1223 337461