Confusing band interpolation results using ypp in tutorial

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Kibyshev
Posts: 3
Joined: Sat Sep 11, 2021 3:01 pm

Confusing band interpolation results using ypp in tutorial

Post by Kibyshev » Thu Sep 16, 2021 10:08 am

Dear all,

I am a beginner in Yambo code, starting from the tutorials in yambo wiki. But I encountered a problem when following the tutorial http://www.yambo-code.org/wiki/index.ph ... rial:_h-BN step 3 to interpolate the band structures using ypp in h-BN. I used the SAVE folder provided in the hBN.tar.gz file, and the ypp_bands.in read

Code: Select all

#      Version 5.0.3 Revision 19584 Hash 1cce2ba63                    
#                       Branch is                                     
#                   MPI+HDF5_IO Build                                 
#               http://www.yambo-code.org                             
#
electrons                        # [R] Electronic properties
bnds                             # [R] Bands
PROJECT_mode= "none"             # Instruct ypp how to project the DOS. ATOM, LINE, PLANE.
INTERP_mode= "NN"                # Interpolation mode (NN=nearest point, BOLTZ=boltztrap aproach)
INTERP_Shell_Fac= 20.00000       # The bigger it is a higher number of shells is used
OutputAlat= 4.716000             # [a.u.] Lattice constant used for "alat" ouput format
cooIn= "rlu"                     # Points coordinates (in) cc/rlu/iku/alat
cooOut= "rlu"                    # Points coordinates (out) cc/rlu/iku/alat
% BANDS_bands
   6 | 11 |                         # Number of bands
%
CIRCUIT_E_DB_path= "none"        # SAVE obtained from the QE `bands` run (alternative to %BANDS_kpts)
BANDS_path= ""                   # High-Symmetry points labels (G,M,K,L...) also using composed positions (0.5xY+0.5xL).
BANDS_steps= 30                  # Number of divisions
#BANDS_built_in                # Print the bands of the generating points of the circuit using the nearest internal point
%BANDS_kpts                      # K points of the bands circuit
 0.33300 |-.66667 |0.00000 |
 0.00000 |0.00000 |0.00000 |
 0.50000 |-.50000 |0.00000 |
 0.33300 |-.66667 |0.00000 |
 0.33300 |-.66667 |0.50000 |
 0.00000 |0.00000 |0.50000 |
 0.50000 |-.50000 |0.50000 |
%
However, the o.bands_interpolated output didn't provided smooth band energy curves, instead, a step-like distribution in the attachments:
band.png
I have tried to change the BANDS_steps to 300, use denser k-grid in pwscf calculation, and add %INTERP_Grid% tag, but none of them helped.

What have I missed in the ypp input file? Coule anyone help me on this?

Best Wishes.
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Ruji Zhao
Institute of Physics (IOP)
University of Chinese Academy of Sciences
Beijing P.R.China

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Daniele Varsano
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Joined: Tue Mar 17, 2009 2:23 pm
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Re: Confusing band interpolation results using ypp in tutorial

Post by Daniele Varsano » Thu Sep 16, 2021 11:05 am

Dear Ruji,

you can try to use a different algorithm:

Code: Select all

INTERP_mode= "BOLTZ"

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

Kibyshev
Posts: 3
Joined: Sat Sep 11, 2021 3:01 pm

Re: Confusing band interpolation results using ypp in tutorial

Post by Kibyshev » Thu Sep 16, 2021 11:36 am

Daniele Varsano wrote:
Thu Sep 16, 2021 11:05 am
Dear Ruji,

you can try to use a different algorithm:

Code: Select all

INTERP_mode= "BOLTZ"

Best,
Daniele
Thank you, that works!
But I wonder why the "NN" INTERP_mode fails, is it because the "INTERP_NofNN" tag set to be 1?

Best wishes.
Ruji Zhao
Institute of Physics (IOP)
University of Chinese Academy of Sciences
Beijing P.R.China

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Daniele Varsano
Posts: 2997
Joined: Tue Mar 17, 2009 2:23 pm
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Re: Confusing band interpolation results using ypp in tutorial

Post by Daniele Varsano » Thu Sep 16, 2021 11:59 am

Dear Ruji,

you can tr to play with the nearest neighbour parameters and shell factor, but th BOLTZ algorithm is more powerful and I would go for it anyway.

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

Kibyshev
Posts: 3
Joined: Sat Sep 11, 2021 3:01 pm

Re: Confusing band interpolation results using ypp in tutorial

Post by Kibyshev » Thu Sep 16, 2021 12:13 pm

Daniele Varsano wrote:
Thu Sep 16, 2021 11:59 am
Dear Ruji,

you can tr to play with the nearest neighbour parameters and shell factor, but th BOLTZ algorithm is more powerful and I would go for it anyway.

Best,
Daniele
I understand, thank you for your help!

Best wishes!
Ruji Zhao
Institute of Physics (IOP)
University of Chinese Academy of Sciences
Beijing P.R.China

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