Yambo Community Forum

Sorry,

it didn't load the files before. I am putting the images since the file itself are too heavy.

By the way, I have put them at the both isolevel

Davide

Dear Davide,
you have very localised excitons, with a nearly molecular characters.
Finally looking at weights, the larger contribution comes from same Bloch states 18->19 for both excitons.

In the exciton 5, you have also many contribution at higher energy (17->20), may be you can inspect the valence/conduction bloch states in that region.

The intensity, without normalisation it is quite small, you can try to place in a different place. I would not expect much difference, but you can try.
Note that Yambo does not place the hole exactly in the place you indicated but in the nearest place compatible with the FFT grid, so check if it has not fall in a place of
low valence density.

Best,
Daniele

Dear Daniele,

Thank you very much for your help

I will try to analyze more deeply the second peak then and also I will try to change the position of the hole.

Thanks again,

Davide

Anyway,
the shape and localisation, when seen in 3D are not exactly the same.
I would say that all is consistent.

Best,
Daniele

Dear Daniele,

Just another quick question: the quantity which is plotted is the actual excitonic wavefunction or the modulus squared of the excitonic wavefunction?

Best,

Davide

Dear Davide,
it is the modulus squared.

Best,
Daniele

Dear Developers,

I write again regarding excitons such polymers and asking for your advice.
I considered another one with more benzene rings and plotted the singlet with ypp via:

excitons # [R] Excitons
wavefunction # [R] Wavefunction
Format= "x" # Output format [(c)ube/(g)nuplot/(x)crysden]
Direction= "123" # [rlu] [1/2/3] for 1d or [12/13/23] for 2d [123] for 3D
FFTGvecs= 600 Ry # [FFT] Plane-waves
States= "1 - 2" # Index of the BS state(s)
BSQindex= 1 # Q-Index of the BS state(s)
Degen_Step= 0.010 eV # Maximum energy separation of two degenerate states
% Cells
17 | 1 | 1 | # Number of cell repetitions in each direction (odd or 1)
%
% Hole
10.565 | 18.897 | 9.449 | # [cc] Hole position in unit cell

The result is in the figure attached. I don't know how to interpret the huge electron density on the exterior of the polymer.
Is it physical? Or I might have done something wrong?

All parameters for BSE as well as vacuum and k-points have been properly converged.

Thanks in advance,

Davide Romanin
-----------------------------------------------------
Post-doctoral fellow
Institut des NanoSciences de Paris
Sorbonne Université, CNRS
4 place Jussieu,
75252 PARIS Cedex 05

Dear Davide,
most probably is just a matter of isosurface value and if you raise your isosurface value they disappear.
Other option is that you are placing the hole in a region of poor density and in this way you have numerical noise. Note that
exc-wf are normalised to its maximum. Looking at the weights of the transition forming your exciton, be sure to place the hole
in a regione where the valence density is significant.

Best,
Daniele