[CP2K-user] [CP2K:13942] Large energy difference between md step and single point calculation

[HB H]

*Hi  Massimo,*

I think in MD simulations, the energy of one step is calculated not only
based on the geometry, but also wavefunction of the last step. While the
single point calculation only relies on the geometry.

That being said, you should save the wfn files of each MD steps and use
them as the restart wfn for single point calculations.(i.e. add "
*WFN_RESTART_FILE_NAME* *XXXXX-RESTART.wfn*" in "DFT" section)

Let know if I was wrong or not.

Cheers,
Haibei


Massimo Bocus <massib... at gmail.com> 于2020年9月22日周二 下午4:55写道：

> Dear CP2K users/developers,
>
> I am extracting some snapshots from an umbrella sampling simulation (with
> PLUMED as dependency of CP2K 5.1) and I would like to recalculate their
> energy at a higher level of theory. So to start I performed a single point
> calculation at the same level of theory of the US simulation (PBE-D3) and,
> surprisingly for me, I got very different results in the energy. In
> particular, the energy of the MD step is:
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):
> -3520.987951048081868
> While for the single point calculation:
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):
> -3520.903314334958850
> Which is an enormous difference. Attached the two input scripts, the main
> differences being the RUN_TIPE, the cell parameters (for the single point
> they are just taken from the md output at the selected step) and the lack
> of the MOTION section.
> Does anybody have an idea on where this large energy difference could come
> from?
>
> Thank you in advance,
> Massimo Bocus
>
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