[Wannier] A question on the Hamiltonian with spinors from Wannier90

[Julen Ibanez Azpiroz]

Dear Binghai,

Maybe the issue is related to the convergence, the off-diagonal matrix
elements you show have a non-null imaginary part, as far as I know this
means that the Wannier functions you got are not still the maximally
localized ones since these should be real in a system with TR symmetry (see
PRL 98, 046402 (2007)). Maybe you could try to wannierise till the
imaginary part of the matrix elements are null to be sure that you got the
MLWF, and then check the on-site and off-diagonal matrix elements. Just a
question, the 16 bands you are including, are they all below the Fermi
level?

Cheers,

Julen


On Fri, Nov 9, 2012 at 11:44 AM, Yan, Binghai <yanb at uni-mainz.de> wrote:

> Dear Wannier developers
>
> I am new user of wannier90. I extract wannier functions from a DFT
> calculation (I use vasp) including spin orbit coupling (SOC). Then I switch
> on spinors=T and double the num_bands.
> My systems have no spin polarization, respecting the time reversal
> symmetry. A wannier function is expected to be represented by two
> functions, which have the same center but different spins. I expect these
> two functions have the same onsite energies and the hopping term between
> them are exactly zero.
> However, I get different onsite energies and nonzero hopping terms,
> although the band structure is well reproduced. The wannier cenceters are
> also very different.
>
> The following is an example of my inputs for bulk HgTe calculations.
> (zincblende structure)
>
> ==========
> num_wann          =   16
> num_bands         =   38
> #exclude_bands     =   3-12
>
> dis_win_max       =  15.0
> dis_froz_max      =  9
> dis_num_iter      =  2000
> dis_mix_ratio     = 1.d0
>
> num_iter          = 1000
> num_print_cycles  = 10
>
> Begin Projections
> Hg : sp3
> Te : sp3
> End Projections
>
> spinors = .true.
>
> begin unit_cell_cart
>      3.2300000     3.2300000     0.0000000
>      0.0000000     3.2300000     3.2300000
>      3.2300000     0.0000000     3.2300000
> end unit_cell_cart
>
> begin atoms_cart
> Hg       2.4225000     2.4225000     2.4225000
> Te       4.0375000     4.0375000     4.0375000
> end atoms_cart
>
> mp_grid =    12    12    12
>
> begin kpoints
>       0.000000000000      0.000000000000      0.000000000000
>       0.083333333333      0.000000000000      0.000000000000
>       0.166666666667      0.000000000000      0.000000000000
>       0.250000000000      0.000000000000      0.000000000000
> ................
> ========================
>
> The optimized wannier centers are :
>  Cycle:   1000
>   WF centre and spread    1  (  1.125081,  2.105459,  2.107134 )
> 7.50544434
>   WF centre and spread    2  (  2.108857,  1.123510,  2.103942 )
> 7.50493864
>   WF centre and spread    3  (  2.106035,  2.107794,  1.122418 )
> 7.50768700
>   WF centre and spread    4  (  1.124096,  1.124214,  1.123910 )
> 7.52064335
>   WF centre and spread    5  (  3.522963,  3.524601,  3.524535 )
> 4.48040046
>   WF centre and spread    6  (  3.526018,  2.934456,  2.939037 )
> 4.47399171
>   WF centre and spread    7  (  2.939672,  3.523541,  2.932669 )
> 4.46863560
>   WF centre and spread    8  (  2.934153,  2.938291,  3.522491 )
> 4.47010302
>   WF centre and spread    9  (  2.107155,  2.105137,  1.125272 )
> 7.64204572
>   WF centre and spread   10  (  1.123133,  1.123929,  1.123907 )
> 7.64532973
>   WF centre and spread   11  (  1.122550,  2.106696,  2.105047 )
> 7.63263662
>   WF centre and spread   12  (  2.104217,  1.123646,  2.107754 )
> 7.63564195
>   WF centre and spread   13  (  3.524860,  3.524017,  3.523515 )
> 4.51698438
>   WF centre and spread   14  (  3.522838,  2.936705,  2.934278 )
> 4.51145886
>   WF centre and spread   15  (  2.933391,  3.524025,  2.938085 )
> 4.50864047
>   WF centre and spread   16  (  2.937251,  2.934720,  3.525198 )
> 4.51260402
>   Sum of centres and spreads ( 38.762270, 38.760740, 38.759191 )
>  96.53718585
>
> For example, the matrix elements between WF 8 and WF 16 are
>
>     0    0    0    8    8    0.863620    0.000000
> -
>     0    0    0   16   16    0.932080    0.000000
> -
>     0    0    0   16    8   -0.032312   -0.000905
> -
>     0    0    0    8   16   -0.032312    0.000905
>
>
> Is this problem due to a bad projection? Actually, I used sp3 for non-SOC
> case, it seems pretty well.
> Is there a way to constrain different spins have the same wannier centers?
>
> Thank you very much in advance!
> Binghai
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-- 
========================================
 Julen Ibañez Azpiroz
 Materia Kondentsatuaren Fisika Saila
 Zientzia eta Teknologia Fakultatea
 Euskal Herriko Unibertsitatea
 ========================================
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