>>The algorithm is as follows:
>>  - if an atom has no charge, then the covalent radius is used
>>    (data values from OpenBabel)
>>  - if an atom has a charge, then it is looked up in the ionic table
>>     * if it is not found in the ionic table, then the
>>       covalent radius is returned
>
> I may have missed (or forgotten) some of this discussion.

Phillip and I probably exchanged a few emails without cc'ing everyone.

Here is the issue ... What happens if I see an element/charge
combination that is not in the table? For example, I open a file which
has a carbon atom with a charge of +7.

Based upon my brief discussion with Phillip, I decided that a
'covalentRadius' was most closely related to a charge of 0 ... therefore
the  default was to use the covalentRadius.

> Are you talking about "used" for determining the presence of a
> covalent bond, or "used" in the spacefill rendering?

Certainly the former ... "used" as the radius for determining
covalent/ionic bonds.

And the latter too, but only for 'spacefill ionic', not for 'spacefill on'.

> If the latter, do you really mean covalent radii?
> As stated in
> http://www.umass.edu/microbio/rasmol/rasbonds.htm
> RasMol uses van der Waals radii or "united atom radii" by default for
> spacefill.
> I think Jmol should do the same for backward compatibility.

Agreed.

'spacefill on' uses vdw radii
  (although the values I am currently using are taken from OpenBabel)

'spacefill ionic' will use ionic/covalent radii

> I've never been clear about the rationale for using vdW radii in
> spacefill  rendering instead of covalent radii.

Certainly *I* don't have any idea :-)


If you think any of this is incorrect behavior, please speak up.


Miguel





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