hybrid DFT for bulk

molecule san... at gmail.com
Thu Jul 24 22:41:34 CEST 2008


Hi, Teodoro

I don't want to argue about the wording.
I just did comparative calculations
using cp2k and g03 for an infinite H chain (1A of separation).
The settings are the same for both calculations:
The unit cell contains 8 H atoms
and its dimension is 8A x 8A x 8A.
The basis set is 6-31G* and 4 shells are used for the periodicity.
xc=b3lyp, k-sampling=\Gamma

E(g03_PBC)= -27.6442625829 A.U.
E(cp2k_PBC)= -4.426086805926252 A.U.

Any comment on this?

cheers,
molecule


On Jul 18, 9:28 pm, Teodoro Laino <teodor... at gmail.com> wrote:
> Dear molecule,
>
> If you consider the gamma point sampling a numerical error.. well..
> guess there's not too much one can comment.. but be cautious to do
> such claims in a more aggressive audience!
>
> Moreover, keep in mind that Juerg also mentioned the 1/r problem for
> the exact exchange.. and since your cell is small.. I wonder.. do you
> consider
> that a numerical problem as well?
> Maybe you think that the whole story of long-range interactions is..
> a numerical error? Eager to know your point of view..
>
> cheers,
> Lost_somewhere_with_more_than_6_hours_delay.
>
> On 18 Jul 2008, at 23:09, molecule wrote:
>
> > However, the behavior looks more like a bug rather than the
> > numerical errors caused by \Gamma-only sampling and the
> > minimum images.


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