[Wannier] large spreeds for some WFs

lan haiping lanhaiping at gmail.com
Thu Nov 23 13:21:58 CET 2006

Dear All,

  I am trying to  study  disentanglement of wannier with nanotube (10 0) by
including several conduction bands.
There are some problems  that i didnot come to for the cases of only valence
bands included.
First , it takes me long time to reach the convergence thread for
disentangle process. I just tried to tune dis_mix_ratio , but there is no
much effect.  In my calculation, I had included 130 bands for disentangling
100 WFs, it would take about 4000 iterations to reach convergence no matter
what dis_mix_ratio i set to.  This value is of course seriouly larger than
the default value (200).
Though there are a few parameters for disentanglement, i donot have much
idea about
energy window settings for disentanglement and frozen energy window. Could
we just set dis_win_min to conduction bands' bottom in my semiconducting cnt
case  ?  I also tried to set frozen energy window , but there was no much
effect for improving convergence. Could  the proper frozen energy window
improve convergence ?  and would you please tell how to set up frozen energy
window properly ?

Another question is about large spreads for some WFs after
wannierise.Afterwannierise process, there are mainly 3 groups of
spreads of WFs. Spreads of
first group are around 0.6- 0.7,  while 1.6-2.4 are for second group. There
are 2 WFs for third group, of  spreads around 7.0 ,which are great larger
than  that of other two group. Does such result have proper physical meaning
Any comments will be appreciated.     As far as i know, large spreads of WFs
may not be suitable for tight binding calculation . Are there any methods or
settings to obtain smaller spreads of  WFs ?

Best Wishes,

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