[CP2K:3169] error in bond dissociation energy of gas phase molecule

hut... at pci.uzh.ch hut... at pci.uzh.ch
Wed Apr 6 13:02:38 CEST 2011


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
> 
> -- 
> You received this message because you are subscribed to the Google Groups "cp2k" group.
> To post to this group, send email to cp... at googlegroups.com.
> To unsubscribe from this group, send email to cp2k+uns... at googlegroups.com.
> For more options, visit this group at http://groups.google.com/group/cp2k?hl=en.
> 
> -- 
> You received this message because you are subscribed to the Google Groups "cp2k" group.
> To post to this group, send email to cp... at googlegroups.com.
> To unsubscribe from this group, send email to cp2k+uns... at googlegroups.com.
> For more options, visit this group at http://groups.google.com/group/cp2k?hl=en.
> 

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To post to this group, send email to cp... at googlegroups.com.
To unsubscribe from this group, send email to cp2k+uns... at googlegroups.com.
For more options, visit this group at http://groups.google.com/group/cp2k?hl=en.




More information about the CP2K-user mailing list