[salmon-user:00328] question about intra-band current

[覃睿]

Dear Salmon developers and users,

Recently I tried to calculate the intraband current when I study a system under laser pulse. According to the referenced paper (T. Otobe, Phys. Rev. B 94, 235152 (2016)), I set 'projection_option=td', and the related settings are as following in the input file:

&analysis

  projection_option='td'

  yn_out_intraband_current='y'

  out_projection_step=50

/  

However, when I finished the calculation and compared the intraband current with the total current, I got the following results. The intraband current is larger than the total current, and has rapid oscillations. 

Could you please give some advice for the intranband current? Is there something wrong with my setting?

Thank you so much!

Rui

[Yamada Shunsuke]

Dear Rui-san,

Thank you for the question. The iteration for the projection wavefunctions seems to be unconverged. 

For better convergence, we can use threshold_projection and nscf. Firstly, pls specify more larger nscf.

(nscf is in the &scf section. the projection subroutine utilize it as the number of the maximum iteration.)

If results are still dirty, pls specify smaller threshold_projection (default=1e-6).

Also, we need to choose nstate carefully to account enough unoccupied orbitals for the projector.

Sincerely,

Shunsuke

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差出人: 覃睿 <qi...@pku.edu.cn>
送信日時: 2025年3月8日 16:43
宛先: salmo...@salmon-tddft.jp <salmo...@salmon-tddft.jp>
件名: [salmon-user:00328] question about intra-band current

 

[Rui Qin]

Dear Yamada,

Thank you so much for the suggestions. I have tested increasing the nscf, nstate, and decreasing threshold_projection. Finally I found the dirty intraband current in former calculation is mainly due to the high threshold_projection (1e-6). When I lower it to 1e-8, I get much smoother intraband current.

Yours sincerely,

Rui

-----Original Messages-----
From: "Yamada Shunsuke" <yamada....@qst.go.jp>
Send time: Saturday, 08/03/2025 16:17:04
To: "salmo...@salmon-tddft.jp" <salmo...@salmon-tddft.jp>
Subject: [salmon-user:00329] Re: question about intra-band current

[Rui Qin]

Dear Yamada,

I have tested the related parameters to get the converged intraband current. The result is shown below. Although the intraband current is quite smooth now, it is overall larger than the total current, which is supposed to be smaller than the total one.

I also calculate the high harmonic spectrum for the intraband and total current like Figure 4 of Otobe's paper(PHYSICAL REVIEW B 94, 235152 (2016)). The HHG result is also shown below. It looks strange that the amplitude of high orders(>=9) from intraband current is much larger than those from total current.

Figure 4 from Otobe's paper

The behaviors of the intraband current and its HHG spectrum look like unphysical. How to interpret this? Maybe there is large inter-band current negative to the intra-band current? Or there's still something wrong in my calculation?

Best regards

Rui

[Yamada Shunsuke]

Dear Rui-san,

Thank you very much for the detailed analysis. This is very helpful.

I would like to investigate the problem. Could you send me your input file?

Sincerely,

Shunsuke

---

差出人: Rui Qin <qi...@pku.edu.cn>
送信日時: Wednesday, March 12, 2025 12:45:41 PM
宛先: salmo...@salmon-tddft.jp <salmo...@salmon-tddft.jp>
件名: [salmon-user:00331] Re: question about intra-band current

 

[Rui Qin]

Dear Yamada,

Sure, the input files for the ground state and time evolution calculations are attached (gs.inp and td.inp) in the email. C.upf is the pseudopotential file from www.pseudo-dojo.org.

Thank you very much for your help.

Yours sincerely,

Rui

-----Original Messages-----
From: "Yamada Shunsuke" <yamada....@qst.go.jp>

Send time: Wednesday, 12/03/2025 12:34:48
To: "salmo...@salmon-tddft.jp" <salmo...@salmon-tddft.jp>
Subject: [salmon-user:00332] Re: question about intra-band current

[Yamada Shunsuke]

Dear Rui-san,

 

Thank you for sharing your input files. I will investigate whether there is a bug or not.

Please wait for a while. It will take some time.

Sincerely,

Shunsuke

---

差出人: Rui Qin <qi...@pku.edu.cn>
送信日時: 2025年3月12日 14:42
宛先: salmo...@salmon-tddft.jp <salmo...@salmon-tddft.jp>
件名: [salmon-user:00333] Re: question about intra-band current