[resending this -- attachments were too large]

Jmol Developers,  -- Eric, Miguel, Jonathan, Egon, Angel, Rolf and others -

I need some feedback here. I think I finally fixed a long-standing
bug/feature in Jmol. But I'm open to suggestions if you think I have gone
too far in that it WILL change the look of Jmol. (We're talking Jmol 11.10
here, not a fix in 11.8)

The problem was noted several years ago, but until today I hadn't figured
out how to approach it properly. In a certain sense there is no "right"
answer here, but I think this fix will go a long way to making the situation
better for more people.

The issue has to do with the fact that the Jmol VDW data set was derived
from OpenBabel 1.0, which has rather inflated values for H, C, N, and O.
These seem to be fine for older PDB files that don't have H atoms, but
people notice the difference with small molecules.

In addition, over time the Babel data set at their site has been updated,
and Jmol is long out of sync with that. I added the OpenBabel 2.1 data set a
while back (set defaultVDW BABEL), and today I noticed that there is still
another, newer, set associated with OpenBabel 2.2.

With the latest code I have checked in you can check this with a new syntax:

load caffeine.xyz
spacefill JMOL        # really old OpenBabel values
spacefill BABEL     # newest OpenBabel values
spacefill BABEL21 # older values; "BABEL" in Jmol 11.8

examples can be found at
http://chemapps.stolaf.edu/jmol/docs/examples-11/new.htm

The real problem is that there is no single VDW set that works well with
both non-H PDB files and with small molecules or PDB files having H
atoms.The JMOL set is nice for non-H PDB files because it accounts for some
of the lost H atoms, but it looks quite odd with small molecules, as has
been mentioned previously on this list.

That's the real problem.

My proposed solution is as follows:

1) update the OpenBabel 2.2 set as BABEL

2) move the older OpenBabel 2.1 set as BABEL21, in case someone wants that

3) keep the oldest OpenBabel 1.0 set as JMOL

4) add a "set DEFAULTVDW AUTO" option (which would be the default behavior),
which preserves the JMOL default for traditional PDB files having no H atoms
but switches to BABEL when hydrogen atoms are present or when the file
doesn't have residues.

5) make the default VDW radii model-dependent, so if you open caffeine and
1CRN.PDB and 1CDR.PDB all will look correct. Caffeine and 1CDR will both
load using the BABEL set; 1CRN will load using the JMOL set.

6) preserve the current SPACEFILL view as "set defaultVDW JMOL" and the
current ball&stick view as "spacefill 20%JMOL"

Be assured that all STATE scripts saved to date will restore to their exact
previous state -- no change there. However,  just reading new files will
show a slight difference in size of atoms.

I've put up some images so you can see the difference:

http://chemapps.stolaf.edu/jmol/docs/img/caffeine-JMOL.png
http://chemapps.stolaf.edu/jmol/docs/img/caffeine-BABEL.png
http://chemapps.stolaf.edu/jmol/docs/img/caffeine-BABEL21.png


Note that the default ball&stick rendering of Jmol was 20%JMOL, so this
change of parameters changes the standard ball and stick look as well, not
just spacefill 100%. The BABEL set is (appropriately) smaller radii, so I'm
suggesting we set the default radius to 23%BABEL. This matches the C radius
pretty closely. Compare:

spacefill 20%JMOL
spacefill 23%BABEL

http://chemapps.stolaf.edu/jmol/docs/img/caffeine-JMOL-20percent.png
http://chemapps.stolaf.edu/jmol/docs/img/caffeine-AUTO-23percent.png

I happen to think the difference is quite subtle, but there is a difference,
and I'd like comments about whether you feel it's a big deal or not.


Thanks,

Bob


-- 
Robert M. Hanson
Professor of Chemistry
St. Olaf College
1520 St. Olaf Ave.
Northfield, MN 55057
http://www.stolaf.edu/people/hansonr
phone: 507-786-3107


If nature does not answer first what we want,
it is better to take what answer we get.

-- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900



-- 
Robert M. Hanson
Professor of Chemistry
St. Olaf College
1520 St. Olaf Ave.
Northfield, MN 55057
http://www.stolaf.edu/people/hansonr
phone: 507-786-3107


If nature does not answer first what we want,
it is better to take what answer we get.

-- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900
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