## How to understand the unit in X/Im[cm/stV] ?

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AmberLee123
Posts: 5
Joined: Sun Jul 26, 2020 7:00 am
Location: Xiamen, Fujian, China

### How to understand the unit in X/Im[cm/stV] ?

Dear Yamboers,

I am trying the final step in all o.YPP-X_probe_order_Y (Y=0,1,2,3,4) file
http://www.yambo-code.org/wiki/index.ph ... r_response

and I got the line in all
# E [eV] X/Im[cm/stV](x) X/Re[cm/stV](x) X/Im[cm/stV](y) X/Re[cm/stV](y) X/Im[cm/stV](z) X/Re[cm/stV](z)

I have no idea what cm/stV stands for, and how should I convert the value to SI unit (Second order susceptibility V/m). I cannot find it in the yambo wiki page about unit either.

Thank you!
Dr. Guoyu Yang
School of Science, Jimei University, Xiamen, Fujian, China

claudio
Posts: 368
Joined: Tue Mar 31, 2009 11:33 pm
Contact:

### Re: How to understand the unit in X/Im[cm/stV] ?

Dear Guoyu Yang

in Yambo the non-linear response functions are in the gaussian system of units, for example χ2 is in cm/statvolt.

In order to convert the non-linear coefficients between different system of units, you can have a look at the
Appendix C of the book "Non-linear optics" by Robert W. Boyd.

best
Claudio
Claudio Attaccalite
[CNRS/ Aix-Marseille Université/ CINaM laborarory / TSN department
Campus de Luminy – Case 913
13288 MARSEILLE Cedex 09
web site: http://www.attaccalite.com

Yambohne
Posts: 3
Joined: Fri Mar 12, 2021 2:54 pm

### Re: How to understand the unit in X/Im[cm/stV] ?

Hello,

I think the question was also why in every order of the output file the unit is cm/stV instead of (cm/statV)^{n-1} (which by the way it was in the lumen code).

Is this a mistake or is the output now always cm/stV for every order?
Justus-Liebig-University Gießen

claudio
Posts: 368
Joined: Tue Mar 31, 2009 11:33 pm
Contact:

### Re: How to understand the unit in X/Im[cm/stV] ?

Dear Yambohne

I think this is a mistake I will check the code and correct it,
units should be the same of lumen

best
Claudio
Claudio Attaccalite
[CNRS/ Aix-Marseille Université/ CINaM laborarory / TSN department
Campus de Luminy – Case 913
13288 MARSEILLE Cedex 09
web site: http://www.attaccalite.com