### Re: non-linear response

Posted:

**Wed Jul 03, 2019 9:41 am**I will send in your email...

With regards,

Sitangshu

With regards,

Sitangshu

Welcome to the Yambo forum! Post requests, look for help, and discuss the code with the community of users and developers.

http://www.yambo-code.org/forum/

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Posted: **Wed Jul 03, 2019 9:41 am**

I will send in your email...

With regards,

Sitangshu

With regards,

Sitangshu

Posted: **Mon Oct 21, 2019 7:33 am**

Dear Professor Claudio

I hope you are fine. Just wanted to share some news with you regarding our latest work on ab initio non linear optical responses in monolayer GaAs:

https://arxiv.org/abs/1910.08443

I hope you will like this.....

With regards

Sitangshu

I hope you are fine. Just wanted to share some news with you regarding our latest work on ab initio non linear optical responses in monolayer GaAs:

https://arxiv.org/abs/1910.08443

I hope you will like this.....

With regards

Sitangshu

Posted: **Mon Oct 21, 2019 8:39 am**

Very good!

Claudio

Claudio

Posted: **Mon Mar 29, 2021 3:51 pm**

Dear Claudio,

How to get all non zero components of SHG spectra? Which variables is for this goal?

For changing frequencies I should change NLEnSteps, right?

Best,

Marzieh

How to get all non zero components of SHG spectra? Which variables is for this goal?

For changing frequencies I should change NLEnSteps, right?

Best,

Marzieh

Posted: **Mon Mar 29, 2021 9:06 pm**

Dear Marzieh

>How to get all non zero components of SHG spectra? Which variables is for this goal?

you select the cartesian direction of the probe field with the variable and then measure the response

in the direction that you want. For example in the AlAs tutorial

http://www.yambo-code.org/wiki/index.ph ... r_response

we put the field in the x,y direction with the input parameter

then we measure the response in the z direction. In such a way we got the X^2_{xyz}.

Notice that in the output file contains also the response in the x, y direction

and therefore from the same calculation you get the X^2_{xyx}, X^2_{xyy} and X^2_{xyz}.

Some of these can be zero due to symmetry reasons. (note that due to the numerical noise the zero components may be very small but slightly different from zero).

>For changing frequencies I should change NLEnSteps, right?

Yes, this are the number of frequency steps in the energy interval between

let me know if it is clear

best

Claudio

>How to get all non zero components of SHG spectra? Which variables is for this goal?

you select the cartesian direction of the probe field with the variable and then measure the response

in the direction that you want. For example in the AlAs tutorial

http://www.yambo-code.org/wiki/index.ph ... r_response

we put the field in the x,y direction with the input parameter

Code: Select all

```
% ExtF_Dir
1.000000 | 1.000000 | 0.000000 | # [NL ExtF] Versor
```

Notice that in the output file

Code: Select all

`o.YPP-X_probe_order_2`

and therefore from the same calculation you get the X^2_{xyx}, X^2_{xyy} and X^2_{xyz}.

Some of these can be zero due to symmetry reasons. (note that due to the numerical noise the zero components may be very small but slightly different from zero).

>For changing frequencies I should change NLEnSteps, right?

Yes, this are the number of frequency steps in the energy interval between

Code: Select all

```
% EnRngeRt
0.00000 | 10.00000 | eV # Energy range
%
```

best

Claudio

Posted: **Mon Mar 29, 2021 9:50 pm**

Dear Claudio,

Thank you for your explanation.

Could you please explain more to make clear for me?

For example which ExtF_Dir are for the X^2_{xyx}, X^2_{xyy} and X^2_{xyz} respectively?

Can we have all non zero components in a calculation or have to calculate separately?

Best,

Marzieh

Thank you for your explanation.

Could you please explain more to make clear for me?

For example which ExtF_Dir are for the X^2_{xyx}, X^2_{xyy} and X^2_{xyz} respectively?

Can we have all non zero components in a calculation or have to calculate separately?

Best,

Marzieh

Posted: **Mon Mar 29, 2021 10:26 pm**

Ok,

in the X^2 you have three direction, two of the incoming fields and one where you measure the response

The field direction determines the first two components and the response the last one.

For example if you set in Yambo field direction

1.0 | 0.0 | 0.0 | ---> you calculate all components X^2_{xx*}

0.0 | 1.0 | 0.0 | ---> you calculate all components X^2_{yy*}

0.0 | 0.0 | 1.0 | ---> you calculate all components X^2_{zz*}

1.0 | 1.0 | 0.0 | ---> you calculate all components X^2_{xy*}

1.0 | 0.0 | 1.0 | ---> you calculate all components X^2_{xz*}

0.0 | 1.0 | 1.0 | ---> you calculate all components X^2_{yz*}

the * correspond to the different direction in the response file o.YPP-X_probe_order_2.

In the o.YPP-X_probe_order_2 you have seven columns:

The first is the energy,

the 2nd and 3rd columns are the imaginary and real part of X^2_{**x}

the 4th and 5th columns are the imaginary and real part of X^2_{**y}

the 6th and 7th columns are the imaginary and real part of X^2_{**y}

where the ** are the direction of the incoming field, see above.

IF wan

in the X^2 you have three direction, two of the incoming fields and one where you measure the response

The field direction determines the first two components and the response the last one.

For example if you set in Yambo field direction

1.0 | 0.0 | 0.0 | ---> you calculate all components X^2_{xx*}

0.0 | 1.0 | 0.0 | ---> you calculate all components X^2_{yy*}

0.0 | 0.0 | 1.0 | ---> you calculate all components X^2_{zz*}

1.0 | 1.0 | 0.0 | ---> you calculate all components X^2_{xy*}

1.0 | 0.0 | 1.0 | ---> you calculate all components X^2_{xz*}

0.0 | 1.0 | 1.0 | ---> you calculate all components X^2_{yz*}

the * correspond to the different direction in the response file o.YPP-X_probe_order_2.

In the o.YPP-X_probe_order_2 you have seven columns:

The first is the energy,

the 2nd and 3rd columns are the imaginary and real part of X^2_{**x}

the 4th and 5th columns are the imaginary and real part of X^2_{**y}

the 6th and 7th columns are the imaginary and real part of X^2_{**y}

where the ** are the direction of the incoming field, see above.

IF wan

Posted: **Mon Mar 29, 2021 10:58 pm**

Dear Claudio,

Your explanation was very instructive for me to follow the next steps.

Thank you.

Best,

Marzieh

Your explanation was very instructive for me to follow the next steps.

Thank you.

Best,

Marzieh

Posted: **Tue Mar 30, 2021 7:45 am**

Dear Marzieh

I added this explanation to the tutorial

http://www.yambo-code.org/wiki/index.ph ... fferent_X2

best

Claudio

I added this explanation to the tutorial

http://www.yambo-code.org/wiki/index.ph ... fferent_X2

best

Claudio

Posted: **Wed Mar 31, 2021 9:32 am**

Dear Claudio,

I have several questions.

If I have understood correctly, at the first we should use converged abinit( pwsf) files (with respect ecut, nband and k point). Then we have to do convergence yambo calculation only with respect NLnabd, right?

To get SHG responses at zero frequency, can we put like this?

% NLEnRange

0.000001 | 5.000000 | eV # [NL] Energy range

or

change NLEnSteps variable?

For getting the SHG responses to laser 1064 nm, how to do?

Best,

Marzieh

I have several questions.

If I have understood correctly, at the first we should use converged abinit( pwsf) files (with respect ecut, nband and k point). Then we have to do convergence yambo calculation only with respect NLnabd, right?

To get SHG responses at zero frequency, can we put like this?

% NLEnRange

0.000001 | 5.000000 | eV # [NL] Energy range

or

change NLEnSteps variable?

For getting the SHG responses to laser 1064 nm, how to do?

Best,

Marzieh