[CP2K-user] [CP2K:17857] Re: Vibrational analisys

[Lucas Lodeiro]

Hi Marcella,

I expressed it badly, I want to say that each displaced atomic
configuration needs an energy+gradient calculation, this is 6N
energy+gradient evaluations, plus the minimum energy geometry. Of course
the number of output files is equal to the replica layout, but my problem
is that the number of energy+gradient evaluations into all these replica
outputs is not equal to 6N.
A practical example, I have an 8 atom isolated molecule, so it needs 48
energy+gradient evaluations which are printed in the main output correctly.
I launched this calculation in a node with 20 cores, so the replica layout
is 20 and there are 20 output files. When I see these output files I check
there are 5 energy computations into each output, so there are 5*20=100
energy evaluations. This is the point which makes me worried. I do not
understand why there are that huge amount of energy evaluations when 6N=48.

Regards - Lucas

El mié, 12 oct 2022 a las 4:51, Marcella Iannuzzi (<marci.akira at gmail.com>)
escribió:

>
> Hi Lucas
>
> The number of output files of the type ${projectname}-r-#.out
> should be equal to REPLICA| layout of the replica grid, number of groups
> and not to 6N
>
> Kind regards
> Marcella
>
> On Wednesday, October 12, 2022 at 12:35:08 AM UTC+2 Lucas Lodeiro wrote:
>
>> Hello all,
>>
>> I have a detailed doubt about the files and data printed for a
>> vibrational analysis. AFAIK, the calculation is done by numerical
>> differentiation of gradients (differentiation in both directions and
>> average them) so for a molecule with N atoms it needs 6N calculations,
>> which is clearly printed in the main output. Also, each
>> replica/configurationn (6N) is computed and a particular output is printed
>> for each one.
>> Up to this point everything looks fine, but when I see the particular
>> replica output, there are 5 energy computations into the output... I would
>> expect just one.
>> Why is this happening? Am I missing something?
>>
>> Regards - Lucas
>>
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