error in bond dissociation energy of gas phase molecule

Jun chen... at gmail.com
Thu Apr 7 16:02:53 CEST 2011


Thanks for the comments, Matt.

I can reproduce the number from nist chem database. The functional is
B3LYP, isn't it? It has about 0.2 eV difference from all electron
calculations.
We are a bit skeptical on the pseudopotential, but haven't
investigated it yet. Honestly, I don't think I want to. Our main
project is actually calculating PMF of H2O2 dissociation in water. If
the 0.5 eV error in vacuum is due to pseudopotential, I have no idea
what will happen in water. Hopefully, there is some error
cancellation, as you said.

Jun

On Apr 7, 2:06 pm, Matt W <mattwa... at gmail.com> wrote:
> Just a quick comment - describing these molecules with pseudos is
> difficult, probably much harder than many solid state situations, with
> less chance for error cancellation.
>
> For instance, from the NIST comp chem data base (http://
> cccbdb.nist.gov/), the LANLDZ2 pseudo + basis set gives
>
> H2O2 -> 2OH = 2.01 eV
>
> I guess with the weird oxidation state and small O-O distance (core
> relaxation?) errors are likely...how do other semi-local pseudos do?
>
> Matt
>



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