[Wannier] MLWFs convergence

Arash Mostofi a.mostofi at imperial.ac.uk
Tue Feb 5 10:44:41 CET 2013


Dear Barak,

It looks like you've not found "good" MLWFs, as indicated by (i) the 
presence of a WF with large (14 A^2) spread, and (ii) by their 
relatively large imaginary parts - usually you'd want a maximum Im/Re 
ratio of less than 10^-4.

Things to try include using a better initial guess for the WFs and 
checking whether your system is metallic - if so, you may need to 
include some unoccupied states in the procedure.

Best wishes,

Arash

--
Dr Arash A Mostofi
Departments of Materials and Physics
Deputy Director, CDT on Theory and Simulation of Materials
Imperial College London, London SW7 2AZ, UK
+44 (0)207 594 8154 | www.cmth.ph.ic.ac.uk/people/a.mostofi

On 04/02/2013 21:57, Barak Hirshberg wrote:
> Hello all,
>
> I am new to wannier90 so I apologize in advance if my questions are very
> basic.
> I tried getting MLWFs for some exotic phase of solid nitrogen containing
> 16 atoms in the unit cell.
> I ran wannier90 using the usual steps (i.e scf, nscf, wannier90 -pp
> seedname , pw2wan and wannier90 seedname) all steps ran without errors.
> The convergence on the change in total spread is good (<1E-08) and the
> individual spread for each one of the MLWFs is small (except  for one
> MLWF which had a spread of approx. 14 A^2).
> My question is regarding the imaginary to real ratio I get when I set
> wannier_plot to true.
> Most of the ratios are small but my question is - how small should this
> ratio be in order for me to trust my results? is there an agreed upon
> number?
> Below I attached parts of the output file from wannier90.
>
> Thank you for your help,
>
> Barak
>
>   Cycle:  5000
>    WF centre and spread    1  (  7.567859, 13.209385,  5.184986 )
> 0.70140338
>    WF centre and spread    2  ( 11.864534,  2.278618, -2.460449 )
> 0.64166047
>    WF centre and spread    3  ( -0.133446, -0.555639,  2.986801 )
> 0.64033660
>    WF centre and spread    4  (  4.359931,  0.672690,  0.551732 )
> 0.48062667
>    WF centre and spread    5  ( 18.638641, 10.012513,  0.497543 )
> 0.68097292
>    WF centre and spread    6  (  9.463656,  2.478899, -3.337370 )
> 0.65827224
>    WF centre and spread    7  (  7.069144,  0.683143, -6.104408 )
> 0.84429167
>    WF centre and spread    8  (  2.252814,  2.506412,  3.510224 )
> 0.73001676
>    WF centre and spread    9  (  5.976707,  4.380667, -6.469549 )
> 0.67172371
>    WF centre and spread   10  ( -2.520576,  3.825357,  0.326976 )
> 0.84716836
>    WF centre and spread   11  ( 10.829435,  3.771247,  0.414827 )
> 1.14764352
>    WF centre and spread   12  (  3.897967, -2.232030, -0.882095 )
> 0.71313911
>    WF centre and spread   13  ( 13.669932,  5.960805, -3.614440 )
> 0.47155481
>    WF centre and spread   14  (  9.015682,  2.873530,  1.830847 )
>   14.30450649
>    WF centre and spread   15  (  5.122279, 14.873538,  2.950773 )
> 0.55353800
>    WF centre and spread   16  (  9.250352,  0.595709,  0.211942 )
> 0.66645348
>    WF centre and spread   17  (  3.761323,  1.935894,  4.509434 )
> 0.81316895
>    WF centre and spread   18  (  3.232515, -0.893450,  3.738266 )
> 0.57510801
>    WF centre and spread   19  ( 10.961178,  2.661322, -3.719865 )
> 1.17870421
>    WF centre and spread   20  (  5.492873,  1.927944,  3.718886 )
> 0.71123808
>    WF centre and spread   21  (  7.507156,  3.949742, -6.449655 )
> 1.11159974
>    WF centre and spread   22  ( 11.261905,  3.519431,  0.308644 )
> 0.47013618
>    WF centre and spread   23  ( 10.308404,  3.737657, -0.112274 )
> 0.58726397
>    WF centre and spread   24  (  8.052747, 12.472645, -4.224751 )
> 0.70633150
>    WF centre and spread   25  (  2.277564,  2.051127,  3.292008 )
> 0.73620715
>    WF centre and spread   26  (  3.933376,  1.845007,  3.987369 )
> 1.15147471
>    WF centre and spread   27  (  8.408614,  3.836919, -0.031494 )
> 0.59602638
>    WF centre and spread   28  (  8.502460,  2.619604, -3.561032 )
> 0.57692434
>    WF centre and spread   29  (  1.213978, -0.966982,  4.068486 )
> 0.46384431
>    WF centre and spread   30  (  0.812985,  2.795220,  2.323947 )
> 0.78481396
>    WF centre and spread   31  (  9.362818,  4.213889, -0.596837 )
> 0.71086794
>    WF centre and spread   32  (  2.256623, -0.752927,  3.666298 )
> 0.65795028
>    WF centre and spread   33  (  3.268599,  0.602871,  0.897235 )
> 0.64943437
>    WF centre and spread   34  (  2.312072,  0.587473,  0.733080 )
> 0.57851643
>    WF centre and spread   35  (  3.174186,  0.327877,  0.513949 )
> 0.71845087
>    WF centre and spread   36  (  1.230894,  2.388472,  3.060560 )
> 0.54428639
>    WF centre and spread   37  ( 12.406710,  3.326484,  0.409441 )
> 0.69200745
>    WF centre and spread   38  (  4.166060, 11.806127,  3.336140 )
> 0.65540410
>    WF centre and spread   39  ( -1.004998,  3.438282,  5.602983 )
> 0.70211214
>    WF centre and spread   40  (  2.601769,  3.735709, -0.042780 )
> 0.57592436
>    Sum of centres and spreads (241.826723,136.501179, 21.026376 )
>   41.70110400
>
>    10000    -0.201E-08     0.0000966104       41.7011040049     887.91
>   <-- CONV
>          O_D=     13.6361991 O_OD=      4.3130872 O_TOT=     41.7011040
> <-- SPRD
>   Delta: O_D= -0.1586503E-07 O_OD=  0.1385583E-07 O_TOT= -0.2009195E-08
> <-- DLTA
>
>   *---------------------------------------------------------------------------*
>   |                               PLOTTING
>       |
>   *---------------------------------------------------------------------------*
>
>
>        Wannier Function Num:    1       Maximum Im/Re Ratio =    0.737655
>        Wannier Function Num:    2       Maximum Im/Re Ratio =    0.002504
>        Wannier Function Num:    3       Maximum Im/Re Ratio =    0.144278
>        Wannier Function Num:    4       Maximum Im/Re Ratio =    0.006826
>        Wannier Function Num:    5       Maximum Im/Re Ratio =    0.005917
>        Wannier Function Num:    6       Maximum Im/Re Ratio =    0.004897
>        Wannier Function Num:    7       Maximum Im/Re Ratio =    0.018413
>        Wannier Function Num:    8       Maximum Im/Re Ratio =    0.024555
>        Wannier Function Num:    9       Maximum Im/Re Ratio =    0.015222
>        Wannier Function Num:   10       Maximum Im/Re Ratio =    0.242072
>        Wannier Function Num:   11       Maximum Im/Re Ratio =    0.003346
>        Wannier Function Num:   12       Maximum Im/Re Ratio =    0.019909
>        Wannier Function Num:   13       Maximum Im/Re Ratio =    0.001985
>        Wannier Function Num:   14       Maximum Im/Re Ratio =    0.306586
>        Wannier Function Num:   15       Maximum Im/Re Ratio =    0.000646
>        Wannier Function Num:   16       Maximum Im/Re Ratio =    0.002499
>        Wannier Function Num:   17       Maximum Im/Re Ratio =    0.013166
>        Wannier Function Num:   18       Maximum Im/Re Ratio =    0.000000
>        Wannier Function Num:   19       Maximum Im/Re Ratio =    0.004572
>        Wannier Function Num:   20       Maximum Im/Re Ratio =    0.004088
>        Wannier Function Num:   21       Maximum Im/Re Ratio =    0.022775
>        Wannier Function Num:   22       Maximum Im/Re Ratio =    0.000948
>        Wannier Function Num:   23       Maximum Im/Re Ratio =    0.002689
>        Wannier Function Num:   24       Maximum Im/Re Ratio =    0.632958
>        Wannier Function Num:   25       Maximum Im/Re Ratio =    0.022515
>        Wannier Function Num:   26       Maximum Im/Re Ratio =    0.046124
>        Wannier Function Num:   27       Maximum Im/Re Ratio =    0.005474
>        Wannier Function Num:   28       Maximum Im/Re Ratio =    0.005333
>        Wannier Function Num:   29       Maximum Im/Re Ratio =    0.000938
>        Wannier Function Num:   30       Maximum Im/Re Ratio =    0.009628
>        Wannier Function Num:   31       Maximum Im/Re Ratio =    0.001206
>        Wannier Function Num:   32       Maximum Im/Re Ratio =    0.001497
>        Wannier Function Num:   33       Maximum Im/Re Ratio =    0.004265
>        Wannier Function Num:   34       Maximum Im/Re Ratio =    0.000949
>        Wannier Function Num:   35       Maximum Im/Re Ratio =    0.002490
>        Wannier Function Num:   36       Maximum Im/Re Ratio =    0.041489
>        Wannier Function Num:   37       Maximum Im/Re Ratio =    0.004751
>        Wannier Function Num:   38       Maximum Im/Re Ratio =    0.000714
>        Wannier Function Num:   39       Maximum Im/Re Ratio =    0.075279
>        Wannier Function Num:   40       Maximum Im/Re Ratio =    0.029666
>
>
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