[CP2K:3167] error in bond dissociation energy of gas phase molecule

[Teodoro Laino]

Hi Juerg,

the species are not charged - these are all homolytic dissociations.
Nonetheless the H2O2 may have quite a strong dipole and the decoupling may affect the energetics.

Just a comment: WAVELET is not superior to MT. The main difference is the cell size. For such small molecules MT may even be better because you can use a smaller cell or at least comparable to the one of WAVELET :).

Teo

On Apr 6, 2011, at 12:53 PM, hut... at pci.uzh.ch wrote:

> Hi
> 
> as you are generating charged species you should use a non-periodic
> steup.
> 
> Try PERIODIC NONE in the &CELL section together with
> 
>    &POISSON
>      PERIODIC NONE
>      PSOLVER WAVELET    <- MT and ANALYTIC could also work but this is best
>    &END
> 
> in the DFT section.
> 
> regards
> 
> Juerg
> 
> --------------------------------------------------------------
> Juerg Hutter                         Phone : ++41 44 635 4491
> Physical Chemistry Institute   FAX   : ++41 44 635 6838
> University of Zurich               E-mail:  hut... at pci.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zurich, Switzerland
> ---------------------------------------------------------------
> 
> -----cp... at googlegroups.com wrote: -----
> To: cp2k <cp... at googlegroups.com>
> From: Jun 
> Sent by: cp... at googlegroups.com
> Date: 04/06/2011 12:43PM
> Subject: [CP2K:3165] error in bond dissociation energy of gas phase molecule
> 
> Hello everyone,
> 
> We did some testing calculations on bond dissociation energies of HO-
> OH in vacuum using BLYP and B3LYP. We found a large difference from
> reported results using the same functionals in literature; our numbers
> are about 0.5 eV too small for both functionals. We also cross-checked
> the numbers using gaussian program, indeed cp2k gives smaller bond
> dissociation energy. It is not likely to be BSSE, as we use quite
> large basis set TZV2P and also checked QZV2P. It is obvious that we
> got either the total energy of H2O2 too high or the OH energy too low.
> We checked the energy of H2O --> OH + H, which is very close to what
> we found in literature. So, the problem appears to be the too high
> energy of H2O2.
> Also, we checked CH3-CH3, and found the same: CH3-CH3 bond
> dissociation energy is 0.3 eV too small for both functionals compared
> to literature numbers, while the energy of CH4-->CH3+H agrees well.
> The bond dissociation energies (total energies without ZPE) are
> summarised below, and inputs for H2O2-->2OH (H2O2.inp and OH.inp) are
> uploaded.
>                                 BLYP             B3LYP
> H2O2-->2OH       2.04 eV (2.67)      1.80 eV  (2.27)
> H2O-->OH+H        5.10 eV              5.16 eV (5.2)
> C2H6-->2CH3     3.64 eV (3.92)       3.69 eV (3.97)
> CH4-->CH3+H    4.69 eV (4.77)       4.75 eV (4.67)
> Numbers in parentheses are from literature. The geometry is optimised
> one taken from literature, which is almost the same as optimised by
> cp2k.
> Can anyone comment on this? Many thanks in advance.
> 
> Cheers,
> Jun
> 
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