Efields in P&P simulations

[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

[sdwang]

Dear all,
Any news?...

Thanks in advance!

SD

[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

[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.

[sdwang]

Dear Claudio and Davide,
Thanks for the reply.

Best

SD