[Wannier] Several questions about distentangle process

Janiet Wen janietwen at gmail.com
Thu Nov 9 13:25:34 CET 2006

 Dear developers :

   I have several questions about distentangle process giving in SMV paper.
We should set an energy window for distentangle process , while my question
is about this energy window's setting. Should all bands in the energy window
be included in the distentangle process ?  The nscf calculation includes
'nbnd'    bands, which cannot insure all bands included
in the energy window.  So, how to confirm oneself that all bands  are
included in this energy window ?  Just count bands in this window , and make
sure there are several bands above this window ?
 Another question is about  wannierise process for metal cnt. I just wanna
repeat yongsu's work on pristine cnt , and obtain the minimal basis for cnt.
But there are some problems i donot understand clearly. Just with occupied
bands for wannierise, there is no problem both fo semi/metal cnt to reach
convergence. One of my confusion is why could  wannierise reach
convergence without distentangle process in metal cnt since i just set
'num_wan' to the number of valence bands ?  Why fermi surface effect in
metal cnt donot affect this wannierise process ?  What we need to consider
is the  degenerate bands in distentangle process , is it right ?  Next i
consider '2.5 orbitals per atom'  to distentangle WFs. Just with exact 'nat
X 2.5' bands for 'nscf' calculation , it is difficult to reach convergence
in wannierise process ,
Does this problem relate to 'not all bands inculded in the energy window ' ?

Thanks for your patience and time !
Best Wishes

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