[CP2K:3165] error in bond dissociation energy of gas phase molecule

hut... at pci.uzh.ch hut... at pci.uzh.ch
Wed Apr 6 12:53:45 CEST 2011


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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