[Wannier] Enquiry about Convergence and Projection Centre

Kenan Song kenan.song at icn2.cat
Fri Jun 17 10:59:32 CEST 2016

Dear All,

I am doing the wannierization in order to get the Hamiltonian based on wannier basis sets, which is localized on the atom. May I make some general enquiries?

In my calculation, I did not set up conv_window nor conv_tol flags in the seedname.win file. After the calculation done, I found the band structure perfectly matched that gained by Quantum Espresso. I upload my results into the attachment so that you could refer to it. I checked the convergence of the spread in each iteration in the seedname.wout file and found the following information in the last iteration step.

Sum of centres and spreads (105.100061,219.889174,787.360585 )   566.02278059

1000    -0.429E+00     7.0179531852      566.0228135363    2571.04  <-- CONV
        O_D=     43.7907605 O_OD=    225.4234544 O_TOT=    566.0228135 <-- SPRD
 Delta: O_D= -0.2982138E+00 O_OD= -0.1308025E+00 O_TOT= -0.4290163E+00 <-- DLTA

Regarding the convergence issue, I am not sure whether my calculation is reliable; though I got band structure perfectly match. Would anyone tell me whether I should set up conv_window and conv_tol flags in seedname.win file or not? If I should, what value people usually use for conv_tol? Thank you.

My another enquiry is that should I set up guiding_centres = true in the seedname.win file if I am not sure where the exact projection centre is. I am doing non-collinear calculation (spin-orbit coupling) and I found that wannier90 code could not plot wannier functions for such calculation. Is there any way to determine the correct projection centre?

On the other hand, is it possible to calculate the band structure within a certain smaller energy window (for instance -2 eV ~ 2 eV) by Quantum espresso, rather than within the whole energy span (-12 eV ~6 eV)? I apologise, if I ask something stupid.

Any help will be appreciated.

Kind regards,

Kenan Song
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