error in bond dissociation energy of gas phase molecule

Jun chen... at gmail.com
Wed Apr 6 15:27:45 CEST 2011


I just recalled that we also did the calculations using GAPW. The bond
dissociation energy of H2O2 using BLYP increases to about 2.8 eV. This
result places some doubt on the pseudopotential of O. I should admit
that this GAPW number is subject to some uncertainty because we don't
have much experience on GAPW. We just modified an input sample file
from /cp2k/tests. Could any expert on GAPW  quickly do a testing
calculation on this, please. The optimised geometries can be found in
the input files attached above.
Many thanks,
Jun

On Apr 6, 12:40 pm, Jun <chen... at gmail.com> wrote:
> Thank both of you very much !
> Just quickly recalculated the H2O2 bond dissociation energy using MT.
> The number hardly changes. I will try WAVELET, but don't think it will
> make massive difference either.
> Any other comments?
> Jun
>
> On Apr 6, 12:12 pm, Teodoro Laino <teodor... at gmail.com> wrote:
>
> > ops.. sorry my mistake now..
> > reported relative error is of ~ 1.0E-3 Hartree.. nonetheless..
>
> > On Apr 6, 2011, at 1:09 PM, Teodoro Laino wrote:
>
> > >> Sure -
> > >> but for grid steps (fine density grid on which both decoupler are applied) of 0.2-0.3 Angstrom we are comparing errors of 1.0E-5 (MT) with 1.0E-7(WAVELET).
> > >> Given the intrinsic errors reported by Jun (we are talking about errors of 1.0E-2 Hartree here!) for me the above numbers are comparable (I wish to see all the papers out there with an overall accuracy of 1.0E-5 Hartree :) ).
>
> > >> ciao,
> > >> Teo
>
> > >> On Apr 6, 2011, at 1:02 PM, hut... at pci.uzh.ch wrote:
>
> > >>> My mistake, I thought I had read OH-.
> > >>> Regarding the relative accuracy of the decoupling methods, have a
> > >>> look in the paper  
> > >>> DOI=10.1063/1.2335442
> > >>> where the two methods are compared.
>
> > >>> 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: cp... at googlegroups.com
> > >>> From: Teodoro Laino
> > >>> Sent by: cp... at googlegroups.com
> > >>> Date: 04/06/2011 12:58PM
> > >>> Subject: Re: [CP2K:3169] error in bond dissociation energy of gas phase molecule
>
> > >>> 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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