[cclib-devel] Gaussian pop=regular

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

While I was away, a GaussSum bug report reached me where a user used
'pop=regular' instead of the default pop, or pop=full, which we can
handle.

"pop=regular" is described by the manual as:
"The five highest occupied and five lowest virtual orbitals are
printed, along with the density matrices and a full (orbital by
orbital and atom by atom) Mulliken population analysis. Since the size
of the output depends on the square of the size of the molecule, it
can become quite substantial for larger molecules."

An error occurs when reading in the mocoeffs. The overall problem is
that we assume that mocoeffs contains the MO coefficients of all of
the orbitals up to a particular orbital N, where N is less than or
equal to the total number of MOs.

I feel that adapting mocoeffs to handle the "pop=regular" situation is
one special case too many. Instead, I intend to make sure that cclib
doesn't fail to parse, but avoid setting the 'mocoeffs' attribute.
Users of GaussSum know that they need to use 'pop=full' if they want
to do a population analysis.

Regards,
   Noel