[CP2K-user] [CP2K:14349] Re: Large energy difference between md step and single point calculation

[qi zhang]

Dear Massimo： 
 
   So that's it! Thank you very much for your answer！

qzhang

在2020年12月14日星期一 UTC+8 下午11:41:32<mas... at gmail.com> 写道：

> Dear Qi,
>
> Normally that section simply imposes cp2k to call plumed in order to 
> calculate the biased forces for the simulation, so it does not really 
> matter what is actually the content of the plumed file and it can be used 
> for any type of biased simulation.
>
> Regards,
> Massimo
>
> On Sat, 5 Dec 2020 at 04:30, qi zhang <zq... at gmail.com> wrote:
>
>> 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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