[CP2K:8553] error in computing dissociation energy

katarína stančiaková 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. 


Best,Katarina


Dňa streda, 18. januára 2017 11:45:30 UTC+1 jgh napísal(-a):
>
> Hi 
>
> 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 
> molecules. 
> Be aware that pseudopotentials are known to have problems when 
> comparing energies for systems with different spin multiplicities. 
>
> regards 
>
> Juerg 
> -------------------------------------------------------------- 
> 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 
> <javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----cp... at googlegroups.com <javascript:> wrote: -----To: cp2k <
> cp... at googlegroups.com <javascript:>> 
> From: katarína stančiaková 
> Sent by: cp... at googlegroups.com <javascript:> 
> 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: 
>
> /tests/QS/regtest-hybrid-4/CH3-PBE0_TC.inp 
> /tests/QS/regtest-hybrid-4/CH3-PBE0_TC_LRC.inp 
> /tests/QS/regtest-hybrid-4/CH4-PBE0_TC.inp 
> /tests/QS/regtest-hybrid-4/CH4-PBE0_TC_LRC.inp 
>
> 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 
> suggestions? 
>
> 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 
> (/tests/QS/regtest-hybrid-4/) 
>
>
> Thank you for any help 
> Best, 
> Katarina 
>
>
>
>
>
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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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