[Wannier] about initial projections in seedname.win

[Giovanni Pizzi]

Hi,
I see there are the disentanglement flags - are you also considering conduction bands? The bulk polarisation must be calculated from the WFs obtained from the valence bands only.

Best,
Giovanni Pizzi

--
Giovanni Pizzi
Theory and Simulation of Materials and MARVEL, EPFL
http://people.epfl.ch/giovanni.pizzi
http://nccr-marvel.ch/en/people/profile/giovanni-pizzi

On 25 Mar 2019, at 19:31, Duk-Hyun Choe <hoalad at gmail.com<mailto:hoalad at gmail.com>> wrote:

Dear Wannier developers and users,

 I am new to the Wannier90 code and trying to calculate the polarization of bulk BaTiO3.

 I think the bulk polarization should not depend on the choice of initial projections once the convergence has reached but, strangely enough, the results seem to depend on the initial projections schemes.

 For example, I tested two initial projections for BaTiO3.

Case #1: atomic orbital projections
dis_num_iter = 80000
dis_mix_ratio = 0.9d0
dis_conv_tol = 1.0d-9

conv_window  = 100
conv_tol = 1.0d-9

search_shells = 50

Begin Projections
Ba: s;px;py;pz
O: sp3
End Projections

guiding_centres = true
#num_no_guide_iter = 20

num_iter = 80000
num_print_cycles = 100

use_bloch_phases = F

write_r2mn = true
write_xyz = true

num_bands = 32
num_wann = 16
===========================================

Case #2: random projections
dis_num_iter = 80000
dis_mix_ratio = 0.9d0
dis_conv_tol = 1.0d-9

conv_window  = 100
conv_tol = 1.0d-9

search_shells = 50

Begin Projections
Random
End Projections

guiding_centres = true
#num_no_guide_iter = 20

num_iter = 80000
num_print_cycles = 100

use_bloch_phases = F

write_r2mn = true
write_xyz = true

num_bands = 32
num_wann = 16

===================================================

The only difference in the two input files is the Projections block.

Although both cases are converged, the sum of wannier centers for the occupied bands are different for case 1 and case 2.

Can anyone help me with this?

Any comment and/or suggenstions would be very much appreciated.

Thank you.

Best,

| Duk-Hyun Choe, Post-doctoral fellow,
  Department of Physics, Applied Physics, and Astronomy
  Rensselaer Polytechnic Institute, Troy, NY, USA
  E-mail: hoalad at gmail.com<mailto:hoalad at gmail.com>,  Tel: +1-518-687-4389
  Home: https://sites.google.com/site/dhchoeprofile/
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