error in bond dissociation energy of gas phase molecule

Jun chen... at gmail.com
Wed Apr 6 13:40:47 CEST 2011


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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