Yambo Community Forum

Posted: **Tue Apr 27, 2021 8:57 am**

Dear all,

When I calculate the exciton spatial distribution by ypp -e w, I should fix the position of the hole.
My question is how to calculate when my hole coordinates are negative.
This is the coordinates of my structure:

Code: Select all

C            -0.9843082272        0.0027634025       -0.9642687937
C            -0.9273147084        0.0027628694       -0.9409323059
C            -0.9082547812        0.0027508752       -0.8216156622
C            -0.8514579434        0.0027478710       -0.7974394868
C            -0.8331223728        0.0027651980       -0.6776064043
C            -0.7764543927        0.0027729314       -0.6522924862
C            -0.7589102401        0.0028358998       -0.5342108959
C            -0.8138003470        0.0027569081       -0.8915783241
C            -0.7396384107        0.0027331474       -0.7496139386
C            -1.0777315092        0.0026824966       -0.2269671821
C            -1.0035588910        0.0027725396       -0.0850190185
C            -1.0584689362        0.0026868788       -0.4423804176

And the position of the hole determined by the structure coordinates is (-39.16,0.07,-2.16)
I appreciate your help in advance !

best
wangj

Posted: **Tue Apr 27, 2021 10:09 am**

Dear wangj,

when you set a number of cell repetitions, yambo build the large supercell and translate the position of the hole you assigned in the central cell of the big supercell. Did you define a number of a certain number of cell repetition along the x and z direction?
Furthermore, note that the hole position will be placed in the point of thr FFT grid closest to the point defined in the input.
Best,
Daniele

Posted: **Tue Apr 27, 2021 10:39 am**

Dear Daniele,

I defined 11 of cell repatation along the z direction.
And this is my input(ypp -e w)

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ElecTemp= 0.000000         eV    # Electronic Temperature
BoseTemp= 0.000000         eV    # Bosonic Temperature
StdoHash=  40                    # [IO] Live-timing Hashes
excitons                         # [R] Excitonic properties
infver                           # [R] Input file variables verbosity
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= 128853           RL    # [FFT] Plane-waves
States= "1 - 1"                  # Index of the BS state(s)
En_treshold= 0.000000      eV    # Select states below this energy treshold
Res_treshold= 0.000000           # Select states above this optical strength treshold (max normalized to 1.)
BSQindex= 1                      # Q-Index of the BS state(s)
Degen_Step= 0.010000       eV    # Maximum energy separation of two degenerate states
Weight_treshold= 0.050000        # Print transitions above this weight treshold (max normalized to 1.)
% Cells
 1 | 1 | 11 |                             # Number of cell repetitions in each direction (odd or 1)
%
% Hole
 -36.16 | 0.07 | -2.16 |        # [cc] Hole position in unit cell (positive)
%

According to my structure, I ensure the hole position. But if I calculate in this way, it will report an error

Code: Select all

[ERROR] STOP signal received while in[06.01.01] Real-Space grid setup
[ERROR] Hole coordinates in input must be positive

So, how can I resolve this problom? Is there any way to make the hole position positive?

Thanks!
wangj

Posted: **Tue Apr 27, 2021 11:04 am**

Dear Wangj,

you do not need to translate the hole in the repeated supercell, as this is done by the code according to the number of cell repetition.
Instead of placing the hole in the negative sector, try to place it in the closest cell in the positive sector, e.g translate it by a vector of your cell in such a way it is positive defined.

Best,
Daniele

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