Re: [cclib-devel] etenergies

[Noel O'B. <bao...@gm...>]

On 05/03/07, Karol Langner <kar...@kn...> wrote:
> Well, I guess if we parse the excitation energies, then the total energies of
> the excited states are redundant?
For electronic transitions, we're talking about the vertical
excitation energy. The equilibrium energy of the excited state will
probably be lower (relaxation). But, it would be redundant as you say
if CI is calculating the same thing as TDDFT.

> As to CI calculations, there is some
> specific information about the excited states (for example the coefficients
> for MO excitations).

This sounds like etsecs, but we should check.

> On a related note, I'm in favor of parsing output in a way that makes it clear
> what kind of calcualtion was done. In the case of etenergies, the values can
> come from TD-HF, CI, or any other excited state method - perhaps a string
> attribute such as "etmethod" could label this . The same point for
> scfenergies, which can contain energies from HF, DFT, or whatever, an
> "scfmethod" attribute mmight be useful. Just an idea.

I think you can guess I'm not really keen on this. 'implicit' vs.
'explicit' and so on. Can you think of a 'use case' where this has an
advantage? If the result is always treated in the same way by a
particular algorithm (e.g. convoluting the UV spectrum is the same no
matter what the origin of the data), I think that specialising the
data just makes things more difficult. I know that TD-DFT is much
different than CI, but I'd be worried about going down that route in
general. For example, isn't optimising in internal coordinates
different than optimising in cartesian coordinates? OK, it's not so
different as TD-DFT vs CI, so maybe you're right! :-)

> On Sunday 04 of March 2007 22:16, Noel O'Boyle wrote:
> > I would put them all into etxxx. Is there anything extra or different
> > about a CIS calculation? We are talking about "transitions to excited
> > states" rather than "excited states" themselves, right?
> >
> > On 04/03/07, Karol Langner <kar...@kn...> wrote:
> > > I'd like to open a little discussion about parsing excited states. I
> > > uploaded a CIS job and am wondering on how the parsing of excited states
> > > should look like in cclib. Should etenergies (and the other etxxx
> > > attributes) pick up excited states from any kind of calculation - TDHF,
> > > CI, etc.? Or should there be separate attributes for the different kinds
> > > of calculations. The question is similiar to the one we had earlier -
> > > having mpenergies and ccenergies versus one attribute for correlated
> > > energies.
> > >
> > > Karol
>
> --
> written by Karol Langner
> Mon Mar  5 10:42:04 CET 2007
>