[CP2K:8553] error in computing dissociation energy
stanc... at gmail.com
Wed Jan 18 12:11:35 CET 2017
Thank you for the prompt reply,
just to explain: I performed two sets of tests:
1) I used example input files from CP2K to check if I get the same numbers
as in the TEST_FILES (That's reason why I used SZV basis set there).
2) I tested above mentioned reactions always with the same basis set
(TZVP-MOLOPT), box size, poison solvers, convergence criteria, etc. So I
don't think that this might be a problem.
Since I thought that pseudopotential could be "the problem" I tried to
calculate reaction enthalpy of another simple system: 2CO2 -> 2CO + O2
(using the same settings as for previous reactions) and again compared
results with ADF. The difference was about 16 kcal/mol, so I am a bit
surprised that using pseudopotentials might result in a so large
disagreement on such a small systems.
Dňa streda, 18. januára 2017 11:45:30 UTC+1 jgh napísal(-a):
> to add to the post of Vladimir:
> Be careful with the basis sets (SZV is not reasonable in CH4).
> Be consistent: use the same box and cutoff and Poisson solver for all
> Be aware that pseudopotentials are known to have problems when
> comparing energies for systems with different spin multiplicities.
> Juerg Hutter Phone : ++41 44 635 4491
> Institut für Chemie C FAX : ++41 44 635 6838
> Universität Zürich E-mail: hut... at chem.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zürich, Switzerland
> From: katarína stančiaková
> Date: 01/17/2017 02:07PM
> Subject: [CP2K:8553] error in computing dissociation energy
> Dear CP2K users,
> I did some basic testing on bond dissociation energies on a small set of
> molecules using PBE functional.
> I compared my results with literature (
> http://dx.doi.org/10.1007/s00214-007-0401-8 ) and with results obtained
> using ADF.
> However CP2K results are quite different from my reference and ADF. I
> tried to play with settings (e.g. turn off the periodicity), but this did
> not lead to any improvement.
> Afterwards I decided to do some basic testing, using test files.
> Especially I tested following input files:
> However, for CH4 case I obtained quite a difference between the numbers
> given in txt TEST_FILES, where I assume numbers which I should obtain are
> stores. I tested two versions of CP2K (4.0 and 2.6), and numbers are still
> the same. Now I am struggling what might be wrong. Please, do you have any
> Below you can find example of input files and my data
> (for all cases we assume homolytic dissociation)
> CH3-CH3 -> CH3 + CH3 92.59 (96.79) kcal/mol
> CH3-OCH3 -> CH3 + OCH3 81.48 (87.24) kcal/mol
> CH3-isopropyl -> CH3 + isopropyl 86.01 (89.65) kcal/mol
> OCH3 - isopropyl -> 77.69 (84.08) kcal/mol
> Numbers in parentheses are from literature.
> The results from testing files:
> CH3-PBE0_TC.inp -7.98384 (-7.94392) a.u.
> CH3-PBE0_TC_LRC.inp -7.34353 (-7.34351) a.u.
> cCH4-PBE0_TC.inp -7.35850 (-7.35848) a.u.
> CH4-PBE0_TC_LRC.inp -8.00130 (-7.96099) a.u.
> Numbers in parentheses are from corresponding TXT file TEST_FILES
> Thank you for any help
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> [attachment "CH4-PBE0_TC_LRC.inp" removed by Jürg Hutter/at/UZH]
> [attachment "CH4-PBE0_TC_LRC.out" removed by Jürg Hutter/at/UZH]
> [attachment "geo_opt_isopropyl.inp" removed by Jürg Hutter/at/UZH]
> [attachment "geo_opt_isopropyl.out" removed by Jürg Hutter/at/UZH]
> [attachment "Results.pdf" removed by Jürg Hutter/at/UZH]
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