Bugs item #888841, was opened at 2004-02-01 22:36
Message generated for change (Settings changed) made by migueljmol
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Category: Algorithms
Group: None
>Status: Closed
Resolution: None
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Miguel (migueljmol)
Summary: Incorrectly displays connections between atoms

Initial Comment:
Hi,

I have noticed in a number of pdb files that Jmol (which 
is an absolutely brilliant vis tool... WELL DONE) arbitrarily 
draws a connecting line between atoms making non-
sensicle structures.  Initially thought it was because the 
pdb's were old and had poor format but i have noticed it 
with new files also.  Loaded up the same moleculae in 
Rasmol and the structure loads fine.  So it seems to be 
something related to the default connect algorithm 
between atoms that Jmol uses.  Here are some of the 
files/pdbs that this occurs with.  None of these 
anomolies occur in Rasmol

5cpa.pdb - numerous erroneous atomic connections
1e8a.pdb - forms what looks like a spider wec in a beta 
turn between residues 63-68. 
6adh.pdb
5rsa.pdb

If you can tell me where in the code i could find the 
connect algorithm, i'll fix it for you if you like.

Thanks, keep up the brilliant work !

Dave Chandler
[EMAIL PROTECTED]

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Comment By: Peter Murray-Rust (petermr)
Date: 2004-02-02 14:07

Message:
Logged In: YES 
user_id=125666

This is a complex problem and there is no single fix. IMO 
there are at least three ways of generating connections 
between atoms:
- connect all atoms within bonding distance as generated 
from covalent radii. This is Jmol's default behaviour. A crude 
enhancement (don't know whether Jmol uses it) is to have a 
minimum bonding distance as well - this would suppress 
some of the junk
- take a user-supplied connection table. I am not sure 
whether Jmol can use this - it would certainly be valuable 
and I have rraised it before
- use atom labels and fragment dictionaries. This is common 
in proteins and I suspect is what RasMOL does.

There are several reasons for getting spider webs, such as 
disorder, alternate structures, etc. The underlying structure
(s) can be very difficult to entangle. Sometimes the bonding 
is "real" as in boranes and other clusters.  If connection 
tables are not used in Jmol then I suggest this as  a priority. 
To write a protein perception algorithm within Jmol is a lot of 
work.

petermr

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Comment By: Nobody/Anonymous (nobody)
Date: 2004-02-01 22:48

Message:
Logged In: NO 

Just checked out the latest code (application is what i'm 
running) and it has certainly improved on most of the 
incorrect connections between atoms in 5cpa (still some 
between hetero atoms) but the errors in 1e8a (wierd spider 
web in beta turn) and the other two are sitll present, along 
with most of the other files i've noticed.

Cheers

Dave Chandler ([EMAIL PROTECTED])

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=379133&aid=888841&group_id=23629


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