Exciton analysis

[Dhanjit]

Dear all,
I have been trying to do the ypp calculation to analyse the exciton.
But I am having some issues with in the output file

cat o-3D_BSE.exc_qpt1_weights_at_*

Code: Select all

# Electron-Hole pairs that contribute to Excitonic State 68 for iq=1 more than  5.000000%
#
#                       K-point [iku]                         Weight
# :    0.00000000         0.00000000         0.00000000        0.170892164   
# :   0.624999963E-1     0.108253032         0.00000000        0.623574913   
# :   0.124999993        0.216506064         0.00000000        0.377418816   
# :   0.187499985        0.324759096         0.00000000        0.711636543   
# :  -0.249999985       -0.433012128         0.00000000        0.502409399   
# :   0.124999993         0.00000000         0.00000000        0.317584991   
# :   0.187499985        0.108253032         0.00000000        0.553700149   
# :   0.249999985        0.216506064         0.00000000        0.567887247   
# :  -0.187499985       -0.541265190         0.00000000        0.859183729   
# :  -0.124999993       -0.433012128         0.00000000         1.00000000   
# :  -0.624999963E-1    -0.324759096         0.00000000        0.582013607   
# :    0.00000000       -0.216506064         0.00000000        0.132365316   
# :   0.249999985         0.00000000         0.00000000        0.268746912   
# :   0.312500000        0.108253032         0.00000000        0.744910300   
# :  -0.124999993       -0.649518192         0.00000000        0.739944696   
# :  -0.624999963E-1    -0.541265190         0.00000000        0.896785617   
# :    0.00000000       -0.433012128         0.00000000        0.525171518   
# :   0.374999970         0.00000000         0.00000000        0.358814508   
# :  -0.624999963E-1    -0.757771254         0.00000000        0.808874309   
# :    0.00000000       -0.649518192         0.00000000        0.373740405   
# :  -0.499999970         0.00000000         0.00000000        0.198819488   
#    
#    Band_V             Band_C             Kv-q ibz           Symm_kv            Kc ibz             Symm_kc            Weight             Energy
#    
# 
# 07/17/2023 at 12:59 ypp @ master [start]
# 07/17/2023 at 12:59              [end]
#
# .-Input file  ypp_AMPL.in
# | excitons                         # [R] Excitonic properties
# | amplitude                        # [R] Amplitude
# | ElecTemp= 0.025869         eV    # Electronic Temperature
# | States= "68 - 74"                # Index of the BS state(s)
# | BSQindex= 1                      # Q-Index of the BS state(s)
# | #DipWeight                     #  Weight the contribution to the exciton WFs with the dipoles
# | Degen_Step= 0.010000       eV    # Maximum energy separation of two degenerate states

The transition details are missing. This should have included some numbers as shown in the tutorials.
***One more thing I wanted to know that after running the BSE Screening and BSE Kernel calculation can I directly go to "Bethe-Salpeter on top of quasiparticle energies" module skipping the "scissor" module. If not then how can I get the Scissor value corresponding to my system?
The above exciton analysis has been done skipping the Scissor module.
Any help will be appreciated.

Thanks

[Dhanjit]

Dear all,
I have been trying to do the ypp calculation to analyse the exciton.
But I am having some issues with the output file

cat o-3D_BSE.exc_qpt1_weights_at_*

Code: Select all

# Electron-Hole pairs that contribute to Excitonic State 68 for iq=1 more than  5.000000%
#
#                       K-point [iku]                         Weight
# :    0.00000000         0.00000000         0.00000000        0.170892164   
# :   0.624999963E-1     0.108253032         0.00000000        0.623574913   
# :   0.124999993        0.216506064         0.00000000        0.377418816   
# :   0.187499985        0.324759096         0.00000000        0.711636543   
# :  -0.249999985       -0.433012128         0.00000000        0.502409399   
# :   0.124999993         0.00000000         0.00000000        0.317584991   
# :   0.187499985        0.108253032         0.00000000        0.553700149   
# :   0.249999985        0.216506064         0.00000000        0.567887247   
# :  -0.187499985       -0.541265190         0.00000000        0.859183729   
# :  -0.124999993       -0.433012128         0.00000000         1.00000000   
# :  -0.624999963E-1    -0.324759096         0.00000000        0.582013607   
# :    0.00000000       -0.216506064         0.00000000        0.132365316   
# :   0.249999985         0.00000000         0.00000000        0.268746912   
# :   0.312500000        0.108253032         0.00000000        0.744910300   
# :  -0.124999993       -0.649518192         0.00000000        0.739944696   
# :  -0.624999963E-1    -0.541265190         0.00000000        0.896785617   
# :    0.00000000       -0.433012128         0.00000000        0.525171518   
# :   0.374999970         0.00000000         0.00000000        0.358814508   
# :  -0.624999963E-1    -0.757771254         0.00000000        0.808874309   
# :    0.00000000       -0.649518192         0.00000000        0.373740405   
# :  -0.499999970         0.00000000         0.00000000        0.198819488   
#    
#    Band_V             Band_C             Kv-q ibz           Symm_kv            Kc ibz             Symm_kc            Weight             Energy
#    
# 
# 07/17/2023 at 12:59 ypp @ master [start]
# 07/17/2023 at 12:59              [end]
#
# .-Input file  ypp_AMPL.in
# | excitons                         # [R] Excitonic properties
# | amplitude                        # [R] Amplitude
# | ElecTemp= 0.025869         eV    # Electronic Temperature
# | States= "68 - 74"                # Index of the BS state(s)
# | BSQindex= 1                      # Q-Index of the BS state(s)
# | #DipWeight                     #  Weight the contribution to the exciton WFs with the dipoles
# | Degen_Step= 0.010000       eV    # Maximum energy separation of two degenerate states

The transition details are missing. This should have included some numbers as shown in the tutorials.
***One more thing I wanted to know that after running the BSE Screening and BSE Kernel calculation can I directly go to "Bethe-Salpeter on top of quasiparticle energies" module skipping the "scissor" module. If not then how can I get the Scissor value corresponding to my system?
The above exciton analysis has been done skipping the Scissor module.
Any help will be appreciated.

Thanks

[Daniele Varsano]

Dear Dhanjit,

it is possible that there are no transitions with a weight larger than 5% and this is why they are not reported.
You can set in input the minimum weight to be printed (the default is 5%):
EXCITON_weight_treshold=0.01
will print all transition above 1%

if you set it to zero, you will have all the transitions.

Setting a scissor is alternative to use the QP database. You can set the parameters of the scissor and stretching by plotting E_qp vs E_ks.
see e.g. Step 3 of this tutorial:
https://www.yambo-code.eu/wiki/index.ph ... rial:_h-BN

the scissor will be the difference Gap_gw-Gap_dft and the stretching is obtained by a linear fit.

Best,
Daniele