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Efields in P&P simulations

Posted: Fri Aug 16, 2024 7:26 am
by sdwang
Dear all,
In the Wiki of Yambo, I notice that the Efield in Ypp process is:

Code: Select all

fixsyms                          # [R] Remove symmetries not consistent with an external perturbation
% Efield1
 0.000000 | 1.000000 | 0.000000 |        # First external Electric Field
%
% Efield2
 1.000000 | 0.000000 | 0.000000 |        # Additional external Electric Field
%
Where the "Efield1" Pump and the "Efield2" is Probe.
However, in the following process the Probe is:

Code: Select all

% Field1_Dir
   1.000000 | 0.000000 | 0.000000 |        # [RT Field1] Versor
%
and the pump is:

Code: Select all

% Field2_Dir
 0.000000 | 1.000000 | 0.000000 |        # [RT Field2] Versor
%
My concern is which the sequence of pump and probe in ypp and p&p process is correct?

Thanks!

Shudong

Re: Efields in P&P simulations

Posted: Sun Sep 01, 2024 2:25 pm
by sdwang
Dear all,
Any news?...

Thanks in advance!

SD

Re: Efields in P&P simulations

Posted: Mon Sep 02, 2024 9:57 am
by claudio
Dear Sdwang

notice that in Yambo we consider always the first field the "probe"
and the second field the "pump", so everything is correct.
In this example the pump is along the "y" direction while the probe in the "x" direction

best
Claudio

Re: Efields in P&P simulations

Posted: Mon Sep 02, 2024 1:15 pm
by Davide Sangalli
Let me add that the ordering matters only for the yambo_rt input file, e.g. when you actually perform the real-time simulation.
If you will later use ypp to extract the dielectric function, field 1 is considered as the probe.

Instead, when you use ypp for the "fix-symmetries" step, the order does not matter. The fields polarization in input are just used to check which symmetries are compatible with such field direction.

Best,
D.

Re: Efields in P&P simulations

Posted: Tue Sep 03, 2024 7:49 am
by sdwang
Dear Claudio and Davide,
Thanks for the reply.

Best

SD