### non-linear response

Posted:

**Tue Jan 29, 2019 7:53 am**Dear Sir,

I was trying to do a quick non-linear calculation using 4.3.1 version. Please excuse me for the queries as I am new to nonlinear calculations. I went through the papers on real time BSE in PRB by Claudio Attacallite an others. Initially, I am trying some simple problems with lumen also. It ran properly. But in 4.3.1 version, there are many advances that I am not able to understand. So my queries are for a real time linear response for a simple IPA and no long range correction:

I used the command: yambo_nl -u -F input.in

1. I removed all symmetries. Is that correct approach? TR removal seems to produce

<---> Detected 20 wrong symmetries (out of 24 )

[ERROR] STOP signal received while in :[03.01] Initialization

[ERROR] Use ypp -y to repair the symmetry group and restart Yambo

2. Information about first and additional external electric field are not there in ypp_nl. I guess this is in -q pn?

3. yambo_nl -u does not produce ExtF_kind= " ", Should I need to put this additionally? Also there is no NLstep, NLtime NLintegrator. Putting NLDamping = 0.000000, the code complains:

[ERROR] STOP signal received while in :[03.01] Initialization

[ERROR] Error damping=0 and NLtime<0!!

When I put some finite NLDamping value like 0.15 eV, the code runs and produce o.polarization_F1. When I plot y-plolarization vs time, the plot looks like a sine curve.

Am I doing correct?

With regards,

SItangshu

I was trying to do a quick non-linear calculation using 4.3.1 version. Please excuse me for the queries as I am new to nonlinear calculations. I went through the papers on real time BSE in PRB by Claudio Attacallite an others. Initially, I am trying some simple problems with lumen also. It ran properly. But in 4.3.1 version, there are many advances that I am not able to understand. So my queries are for a real time linear response for a simple IPA and no long range correction:

I used the command: yambo_nl -u -F input.in

1. I removed all symmetries. Is that correct approach? TR removal seems to produce

<---> Detected 20 wrong symmetries (out of 24 )

[ERROR] STOP signal received while in :[03.01] Initialization

[ERROR] Use ypp -y to repair the symmetry group and restart Yambo

2. Information about first and additional external electric field are not there in ypp_nl. I guess this is in -q pn?

3. yambo_nl -u does not produce ExtF_kind= " ", Should I need to put this additionally? Also there is no NLstep, NLtime NLintegrator. Putting NLDamping = 0.000000, the code complains:

[ERROR] STOP signal received while in :[03.01] Initialization

[ERROR] Error damping=0 and NLtime<0!!

When I put some finite NLDamping value like 0.15 eV, the code runs and produce o.polarization_F1. When I plot y-plolarization vs time, the plot looks like a sine curve.

Am I doing correct?

With regards,

SItangshu