error in computing dissociation energy
rybk... at gmail.com
Wed Jan 18 11:33:52 CET 2017
first of all, most results are not that different.
1) Regarding the literature. Surely, different basis sets have been used.
Also please note that CP2K employs pseudopotentials. Truhlar has performed
all-electron calculations. Thus, I would say that the results rather agree,
2) As for the tests, there will be some tolerance margin differing on you
compilation, system etc. So, only the last number looks suspicious,
although not really.
вторник, 17 января 2017 г., 14:07:00 UTC+1 пользователь katarína
> 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 -> 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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