[Wannier] Question about final spreads
Nicola Marzari
marzari at MIT.EDU
Mon Dec 18 03:54:23 CET 2006
Dear Hai-Ping,
I believe Michel Posternak has published a paper on Ti02 Wannier
functions. It would be interesting to compare your results to his.
Our consensus was that the localization functional can display
minima that are not meaningful - usually marked by the fact that the
MLWFs do not look localized, or symmetric, and especially that they are
not real-valued, but are complex-valued. These incorrect minima are
somewhat connected to the fact that there are few points in the BZ where
a smooth continuous choice of phase factors was not achieved.
There are cases when more than one good minimum can exist - the first
one that comes to my mind is benzene, where you can have two equivalent
choices for the location of the three double bonds on the aromatic ring.
It could be that yours is another case - there is more that one
meanigful minimum - and, the notion of "meaningful minimum" is rather
heuristic.
Let us know what you find,
nicola
lan haiping wrote:
> Dear All,
>
> I came to confusion about final results of wannierise procedure.
> I am trying to analyse anatase tio2 wannier function and born charge
> with wannier90.x.
> I performed 2 calculations with 2 different projection functions sets,
> other settings are same. Both reached convergenc (error deltas for total
> Omega are about 1E-10). But the total spreads and wannier centers are
> quite different.
> For my first calculation, i just start with sp2 and pz functions at O
> sites, the total spreads finally obtained is 14.397.
> While for the second calculation, the projetion functions are s/px/py/pz
> functions at O sites, the total spreads finally obtained is then
> 15.2170.
>
> The wannier functions of second calculation could be classed into 4
> groups by spreads , while the conclusion is not hold for the fist
> calculation ( the wannier functions are then classed into 8 groups ).
>
> According to MV paper, the MLWFs reflect structures' symmetry by
> spreads. So, Both 2 calculations are not correct.
>
> Would you please give me some comments ?
> And input files are below :
>
> *num_wann = 16
> num_iter = 2000
> guiding_centres = T
> exclude_bands = 1 2 3 4 5 6 7 8 25 26 27 28 29 30
> begin projections
> O : sp2
> O : pz
> end projections
> begin atoms_cart
> Ti 0.000000000 -0.000000000 0.000000000
> Ti 0.000000000 1.892500000 2.378500000
> O 0.000000000 0.000000000 1.979863400
> O 0.000000000 -0.000000000 7.534136600
> O 0.000000000 1.892500000 4.358363400
> O 0.000000000 1.892500000 0.398636600
> end atoms_cart*
>
> *begin unit_cell_cart
> Ang
> 1.8925 -1.8925 4.757
> 1.8925 1.8925 4.757
> -1.8925 -1.8925 4.757
> end unit_cell_cart
> mp_grid : 6 6 6
> begin kpoints
> ......
> end kpoints*
>
> two final spreads and wannier centers are attached.
>
> *Regards*
>
> Hai-Ping
>
>
>
> --
> Hai-Ping Lan
> Department of Electronics ,
> Peking University , Bejing, 100871
>
>
> ------------------------------------------------------------------------
>
> Final State
> WF centre and spread 1 ( -0.057359, 0.368438, 2.144012 ) 0.81913203
> WF centre and spread 2 ( -0.057359, -0.368438, 2.144012 ) 0.81913201
> WF centre and spread 3 ( 0.207447, 0.000000, 1.889906 ) 1.06292459
> WF centre and spread 4 ( -0.197679, 0.225730, 7.480939 ) 0.95045581
> WF centre and spread 5 ( -0.197683, -0.225729, 7.480937 ) 0.95045348
> WF centre and spread 6 ( 0.383935, 0.000000, 7.384053 ) 0.82485652
> WF centre and spread 7 ( -0.197693, 2.118226, 4.411569 ) 0.95044526
> WF centre and spread 8 ( -0.197669, 1.666767, 4.411555 ) 0.95046140
> WF centre and spread 9 ( 0.383935, 1.892503, 4.508447 ) 0.82485530
> WF centre and spread 10 ( -0.057359, 2.260938, 0.234488 ) 0.81913205
> WF centre and spread 11 ( -0.057359, 1.524062, 0.234488 ) 0.81913192
> WF centre and spread 12 ( 0.207447, 1.892500, 0.488594 ) 1.06292460
> WF centre and spread 13 ( -0.090800, 0.000000, 1.575406 ) 0.88848488
> WF centre and spread 14 ( 0.012349, 0.000000, 7.957177 ) 0.88317336
> WF centre and spread 15 ( 0.012349, 1.892503, 3.935322 ) 0.88317159
> WF centre and spread 16 ( -0.090800, 1.892500, 0.803094 ) 0.88848495
> Sum of centres and spreads ( 0.005703, 15.139999, 57.083998 ) 14.39721976
>
>
> ------------------------------------------------------------------------
>
> Final State
> WF centre and spread 1 ( 0.000000, 0.000000, 1.913455 ) 1.16247952
> WF centre and spread 2 ( 0.000000, 0.000000, 7.509543 ) 1.20049037
> WF centre and spread 3 ( 0.000000, 1.892500, 4.382956 ) 1.20048903
> WF centre and spread 4 ( 0.000000, 1.892500, 0.465045 ) 1.16247952
> WF centre and spread 5 ( 0.000000, 0.000000, 2.004457 ) 1.20048828
> WF centre and spread 6 ( 0.000000, 0.000000, 7.600545 ) 1.16248168
> WF centre and spread 7 ( 0.000000, 1.892500, 4.291955 ) 1.16248025
> WF centre and spread 8 ( 0.000000, 1.892497, 0.374043 ) 1.20048827
> WF centre and spread 9 ( 0.000000, 0.000000, 1.522196 ) 0.75151445
> WF centre and spread 10 ( 0.000000, 0.000000, 7.991803 ) 0.75151691
> WF centre and spread 11 ( 0.000000, 1.892500, 3.900696 ) 0.75151511
> WF centre and spread 12 ( 0.000000, 1.892501, 0.856304 ) 0.75151453
> WF centre and spread 13 ( 0.000000, 0.000000, 2.312422 ) 0.68819033
> WF centre and spread 14 ( 0.000000, 0.000000, 7.201578 ) 0.68819219
> WF centre and spread 15 ( 0.000000, 1.892500, 4.690922 ) 0.68819114
> WF centre and spread 16 ( 0.000000, 1.892502, 0.066078 ) 0.68819026
> Sum of centres and spreads ( 0.000000, 15.139999, 57.083998 ) 15.21070184
--
---------------------------------------------------------------------
Prof Nicola Marzari Department of Materials Science and Engineering
13-5066 MIT 77 Massachusetts Avenue Cambridge MA 02139-4307 USA
tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu
More information about the Wannier
mailing list