Re: [cclib-users] orbital occupation numbers

[Karol L. <kar...@gm...>]

Axel,

The terminology seems to be a little tricky. To be specific, the NO
coefficients that we currently parse (for Gaussian) are those that define
the natural orbital as an eigenvector of the diagonalized density matrix.

Here is an example of the output from out unit tests:
https://github.com/cclib/cclib/blob/master/data/Gaussian/basicGaussian09/water_cis.log#L578

The eigenvalues printed there, I think, are the occupoation numbers you
need (the population in each orbital), although in that particular case
some are negative (maybe because the basis set is so small?). Anyway, we
don't parse them, but we could of course, if that will be useful for you.

Cheers,
Karol

P.S. A new release of cclib (1.3) is coming out soon. Which version are you
using? In any case, this will not make it into 1.3, so you will need to use
the dev version from github.


On Thu, Oct 23, 2014 at 12:07 PM, Axel Schild <axe...@go...>
wrote:

> Hi Karol,
>
> I suppose that NO coefficients and orbital occupation numbers are the
> same, i.e. they should be the diagonals of the diagonalized density
> matrix.For single-determinant methods they are 2 (or 1) and for
> multi-determinant methods they have some value between 0 and 2 (or 1).
>
> At least I cannot think of any other meaning of "NO coefficients", but I
> never heard that term so far.
>
> Thanks, I hope that this feature is available soon as it would be pretty
> nice to use cclib!
>
> Cheers
> Axel
>
> On Thu, Oct 23, 2014 at 2:18 PM, Karol Langner <kar...@gm...>
> wrote:
>
>> Hi Axel,
>>
>> The attribute nocoeffs parses NO coefficients, and only for Gaussian at
>> the moment, I believe. It could be easily extended to other programs,
>> assuming our test logfiles contain the data.
>>
>> If I understand correctly, occupation numbers can be calculated from the
>> NO coefficients. Is that correct?
>>
>> Cheers,
>> Karol
>>
>>
>> On Thu, Oct 23, 2014 at 3:40 AM, Axel Schild <axe...@go...>
>> wrote:
>>
>>> Hi,
>>>
>>> I'm one of the developers of orbkit (
>>> http://sourceforge.net/projects/orbkit). So far, we are using our own
>>> Molden, GAMESS US, Gaussian log-file/fchk-file, and WFN-file parser, but we
>>> thought about (also) using cclib to be able to read all the file formats
>>> that you support.
>>>
>>> However, we need orbital occupation numbers (like those of MCSCF
>>> orbitals or of natural orbitals).
>>>
>>> Is this the data that is stored in the variable <nocoeffs> in the
>>> development version? If so, will it be available for any other than the
>>> GAMESS and Gaussian parsers anytime soon? If not, is this feature planned
>>> to be included?
>>>
>>> Cheers
>>> Axel
>>>
>>>
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>>
>