Exciton weights

[sdwang]

Dear all,
I used yambopy to plot the exciton weights on the bands, and the weights seems very small as attached.
The script related to the exciton weifghts as:
...
## [3.B] Interpolate the values
if Bands_Plot_Interpolate:
fig = plt.figure(figsize=(4,6))
ax = fig.add_axes( [ 0.15, 0.15, 0.80, 0.80 ])
# In case of problems with the interpolation, try to increase lpratio
exc_on_bands = yexc.interpolate(yel,path,states,lpratio=20,f=None,size=1.0,verbose=True)
exc_on_bands.plot_ax(ax,color_bands='grey',c_weights='red',alpha_weights=1.0)
I increased 'size' but it does not work. If I reduced lpratio, the weights are bigger, but the bands are crossed heavily.
How to solve the problem?
Thanks!
SD

[palful]

Dear S. D. Wang,

You are right. There is a slight inconsistency in the tutorial script: the "size" parameter should be given as argument to the "plot_ax" function (method of the bandstructure object "exc_on_bands") and not to the "interpolate" function (method of the excitondb object "yexc").

If you add the "size" argument to "exc_on_bands.plot_ax(...,size=4.,...)", you will see that now the plot will work as intended. Thanks for noticing. The wiki and the script should probably be updated to clarify this point.

Best,
Fulvio

[sdwang]

Dear Fulvio,
I have successfully produced the PBE bands with right weights. How could we import the QP corrections in the 'exc_kspace_plot.py' to obtain the weight on the QP band?
Thanks!

SD

[palful]

Dear SD,

You could just read the quasiparticle database instead of the Kohn-Sham energies, replacing the call to YamboElectronsDB with YamboQPDB such as:

Code: Select all

yqp  = YamboQPDB.from_db(filename='ndb.QP',folder='location/of/database')

and then providing the yqp object to the yexc.interpolate function.

Cheers,
Fulvio

[sdwang]

Dear Palful,
I revised the python script as:
...
exc_on_bands = yexc.interpolate(yqp,path,states,lpratio=55,f=None,size=50,verbose=True)
exc_on_bands.plot_ax(ax,c_bands='black',c_weights='red',size=20,alpha_weights=1.0,linewidths=500,s=300)
...
but it does not work and interpolation stops as:
...
exc_on_bands = yexc.interpolate(yqp,path,states,lpratio=55,f=None,size=50,verbose=True)
File "/home/hipeson/intel/oneapi/intelpython/latest/lib/python3.9/site-packages/yambopy/dbs/excitondb.py", line 1122, in interpolate
k1,k2,k3 = energies.expand_kpts()
AttributeError: 'YamboQPDB' object has no attribute 'expand_kpts'
...

Thanks!

Best

SD