How to do non-scf computation by using CP2K

[Dongbo Wang]

Dear CP2K-users and developers,

Can anyone give me some suggestions about non-scf computation in cp2k? Thank you very much!

Best regards.

Dongbo Wang

[Lenard Carroll]

Not sure from the QM side, I think the self-consistent field is necessary or highly desired for getting to the correct energy, but for calculations which do not require SCF, there's classical MD simulations. Here's an example from CP2K: https://www.cp2k.org/exercises:2018_ethz_mmm:h2o_md

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[Dongbo Wang]

Dear  ASSIDUO Network,

Thanks for your reply. 

Here, the non-scf computation mentioned is based on a converged result from scf computation. And I think this non-scf computation is necessary in some task, for example, computing band structure, DOS and some optical properties for large system. Programs like VASP (ICHARG keyword control it) and PWmat give option to do non-scf calculation. I am not sure CP2K have a same module to do non-scf. If some similar keywords exist, please let me know. Thank you so much.  

Best regards.

Dongbo Wang

[Thomas Kühne]

Dear Dongbo Wang, 

in case you already have a converged WF using the same basis set etc., you can simply 

restart by SCF_GUESS RESTART and set MAX_SCF 1 to do a single diagonalization to 

compute your properties.

Best, 

Thomas Kühne

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Thomas D. Kühne

Dynamics of Condensed Matter

Chair of Theoretical Chemistry

University of Paderborn

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Germany

tdku...@mail.upb.de

+49/(0)5251/60-5726

[Dongbo Wang]

Dear   Thomas Kühne,

I had tried non-scf by means as you mentioned. And a periodic electric field was applied in z direction, so the orbital transformation (OT) method was used to SCF computation (PERIODIC_EFIELD keryword can only be used with OT as mentioned on https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/PERIODIC_EFIELD.html). However, I am not sure whether non-scf computation  is also effective by using OT method or not. Could you give me suggestions?

Best regards.

Dongbo Wang 

[Matt W]

I haven't tried this - but if you set the minimizer to SD (steepest descent) and pick a tiny stepsize value along with the MAX_SCF 1 as Thomas suggested you should get a non-scf calc.

Matt