Grimme correction and supercell

[Andrzej]

Dear users,

I performed some calculation for graphite, just for testing some
features.
Here are some results obtained from single point calculations made for
experimenrtal crystal structure under periodic conditions.
Calculations were performed for single unit cell (111), and extended
unit cells: 222, 332 and 442.

Here are values of dispersion (Grimme) energy per C atom.

111: -0.004719
222: -0.0041627
332: -0.00405803
442: -0.00405803

As the calculations were performed under periodic conditions I would
expected that all these values should be the same. Grimme correction
is purely classical expression independent of electron density,
cutoff, lack of k-point sampling and so on.

I will be grateful for any comment.

Andrzej

[Axel]

but it is not independent of minimum image convention and
the classical cutoff. i haven't checked the cp2k implementation,
but the equivalent code in cpmd would provide an option to
compute the real space interactions across multiple copies of
the principle unit cell, so that for small unit cells, you
would still be able to compute those interactions up to a
significant distance beyond the restrictions of using only
the closest image.

cheers,
axel.

[Teodoro Laino]

The neighbor list is always built across all possible periodic images
included within the CUTOFF specified
for the dispersion (as long as you don't have PERIODIC NONE in the &CELL
section! this case would
explain the problem then..)
.
The problem must be somewhere else..
Could you please post a simple input file for both cases (111 and 422) ?
Thanks
Teo

[Andrzej]

Dear Theo,
thanks for answering my questions.

I have uploaded gra_grim.tar file with inputs and outputs.

The last one (442) is calculated with revpbe, but I think it doesn't
matter, as it uses the same parametrization for Grimmie correction as
pbe.

Andrzej

[Teodoro Laino]

Andrzej,

I asked my nephew (named Giovanni, almost 7) to multiply the following
two numbers:

0.16665*5

after some time, extremely proud, he came back with the answer !! On a
couple of sheets of paper he wrote

0.16665*5 = 0.83325
(of course with all details and the proper algebra..)

I had a quick look to your input files and well.. you wrote 0.8333..

You can't expect to get the same energy per atom if the coordinates are
different.. (when you build
the NNN systems you have to handle EXACTLY the proper operations if you
wanna get the right
numerics!!!)

Anyhow.. after correcting this issue the result is just PERFECT.
Thanks for making feel my nephew proud and useful to this world! :-)

Teo

[Daniele Passerone]

Dear Teo,

On 17 Mrz., 20:47, Teodoro Laino <teodoro.la...@gmail.com> wrote:
> Andrzej,
>
> I asked my nephew (named Giovanni, almost 7) to multiply the following
> two numbers:
>
> 0.16665*5
>

(..cut...)
>

please allow me a comment to this post. Note that this comment does
not clash with my respect and appraisal for the invaluable developing
work and continuous support by the cp2k team; but this premise is not
necessary, since we are friends for almost a decade now.

In no case an arrogant and provoking answer like the one you gave to
the user Andrzej is productive or meaningful in the context of a
scientific forum like this one.

You could have delivered the same interesting piece of information
(from which many users will take advantage) in a completely different
way.
Such attitude only contributes to repel people: not only they will
check carefully their input and output files, and the documentation,
before posting (which is a very positive thing!!!), but they will be
so afraid of getting offended, that they will probably move to other
communities...
and this is not what we want, correct?

It seems that some people transform when they drive a car and they
start to get competitive, others transform when they are in the
stadium and they become aggressive....
maybe in the case of computational scientists we could speak about
"support forum-induced almightiness"?


Best,
Daniele

[Teodoro Laino]

Dear Daniele,

> please allow me a comment to this post. Note that this comment does
> not clash with my respect and appraisal for the invaluable developing
> work and continuous support by the cp2k team; but this premise is not
> necessary, since we are friends for almost a decade now.
>

sure! this is a forum where the key-point is the freedom of doing
everything you want.. not moderated.. and you can comment every single
message according your personal convictions.

> In no case an arrogant and provoking answer like the one you gave to
> the user Andrzej is productive or meaningful in the context of a
> scientific forum like this one.
>

My answer was not arrogant neither provocative.
Are you so naive to think that I was insulting Andrzej for a mistake
done in an input file?
Do you really think that I was thinking that Andrzej does not know how
to multiply two numbers while he is
able to run CP2K in an extremely good way ?
Sorry.. but you overlooked that.. and to me it was clear that it was
just a mistype when multiplying the two numbers..
in fact 0.16666*5 = 0.8333 which is the number used in the input file
(instead of 0.83325).
And if you were spending 10 minutes of your time downloading the input
files and checking things, you wouldn't have written this comment, since
it was clear to you as well.

I'm free to joke on a mistake like this one, exactly like you are free
to post your comments.
Remember FREEDOM!

> You could have delivered the same interesting piece of information
> (from which many users will take advantage) in a completely different
> way.
>
> Such attitude only contributes to repel people: not only they will
> check carefully their input and output files, and the documentation,
> before posting (which is a very positive thing!!!), but they will be
> so afraid of getting offended, that they will probably move to other
> communities...
> and this is not what we want, correct?
>

Thanks for the psychological lesson. Maybe in another forum like
"psychological deficits in forum threads" would be more appropriate.
If you really believe what you are saying.. So.. why aren't you moving
out of Switzerland just because few people in Bern offend immigrants?
Maybe 'cause you have some convenience to stay and live here.. The same
applies for users and codes..

I still believe that the message above was not offensive at all, and if
somebody feels like offended.. well..
maybe he has a guilty conscience.
He can always ignore my messages since I'm not CP2K.. like CP2K is not
any of the developers.
And more than staying with CP2K because we do care about the
psychological health of our users, I would like
that people working with CP2K would stay with it because they discovered
a different and more convenient way of doing calculations.

Moreover, IMHO, a discussion forum is not a place where every single
fart coming out of your brain has to be posted.
There are people that put part of their time in reading and trying to
solve serious issues. This time is free time. And people
employ it in the way they like it more.

The one mentioned by Andrzej in principle was sounding like a serious
one. I was pleased to have a look at it,
even though at the very end it turned out to be a human error.
The way I answer is just my personal choice. If you will give me a
proper surcharge to my salary I may even think about building up more
psychological aware answers :-) .

I hope Andrzej will stay with CP2K. If he will decide to move for
another code where people are more responsive or more
aware about the psychological problems of the users, I cannot do
anything else than wishing him all the success.

> It seems that some people transform when they drive a car and they
> start to get competitive, others transform when they are in the
> stadium and they become aggressive....
> maybe in the case of computational scientists we could speak about
> "support forum-induced almightiness"?
>

in this framework.. what is your role? do you feel like the police-forum
that arrest the aggressive guys in the stadium or the competitive guys
on the street?

I just find terribly amazing/funny that if people are not responsive..
one complains about the non-responsiveness.. if somebody is responsive
(and the CP2K forum is EXTREMELY responsive compared to other forums)..
then you complain about the psychological impact of the answers..

Teo
>
> Best,
> Daniele
>
>
> >
>