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

[qi zhang]

Dear Massimo：

Recently I’m trying to use CP2K and the PLUMED plugin to run umbrella 
sampling MD and build the PMF curve for my system. I also restraint the 
distance of two atoms in my system. From your md.inp I see you use plumed 
at MOTION / FREE_ENERGY / METADYN section,  but when I look over the manual 
of cp2k, I find METADYN is the section that sets parameters to set up a 
calculation of metadynamics. I get confused.  Does this mean that the part 
is designed for metadynamics? Or when using CP2K to run dynamics, just look 
at the methods in Plumed.dat and don't worry about the limitations of the 
section? 

Could you please give me some guidance? Thank you in advance.

qzhang


在2020年9月22日星期二 UTC+8 下午4:55:14<mas... at gmail.com> 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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