[MMTK] HarmonicDihedralRestraint problems

[Konrad Hinsen]

On 08.04.2009, at 18:25, Qadir Timerghazin wrote:

> In fact, there are _two_ water molecules in my example, so there are 6
> atoms. The constrain is defined with:
> universe[0].H1, universe[0].O, universe[1].O, universe[1].H1 - note
> [0] and [1] indexes.

Ah, I see - that's in fact due to a bug in MMTK. Your script has two  
assignments to universe.molecule. The second one should overwrite the  
first one so that there is only one molecule in the end. I fixed this  
bug, so your water script will not work with future MMTK releases.  
You should use different attributes for each molecule:

	universe.mol1 = Molecule('water')
	universe.mol2 = Molecule('water')

or use anonymous molecules:

	universe.addObject(Molecule('water'))
	universe.addObject(Molecule('water'))

> FF modification file, which is inconvenient to post. Below is a
> protein example, which segfaults with the dihedral constraint.

That was in fact a trivial typo that was easy to fix. The fix will be  
in future releases, but you can apply the attached patch file to your  
current release as well.

Konrad.
--
---------------------------------------------------------------------
Konrad Hinsen
Centre de Biophysique Moléculaire, CNRS Orléans
Synchrotron Soleil - Division Expériences
Saint Aubin - BP 48
91192 Gif sur Yvette Cedex, France
Tel. +33-1 69 35 97 15
E-Mail: hinsen at cnrs-orleans.fr
---------------------------------------------------------------------


diff -r 45a5e9e687bb MMTK/ForceFields/Restraints.py
--- a/MMTK/ForceFields/Restraints.py	Tue Apr 14 14:40:20 2009 +0200
+++ b/MMTK/ForceFields/Restraints.py	Wed Apr 15 09:28:58 2009 +0200
@@ -163,7 +163,7 @@
          params = self.evaluatorParameters(universe, subset1, subset2,
                                            global_data) 
['cosine_dihedral_term']
          assert len(params) == 1
-        indices = Numeric.array([params[:4]])
-        parameters = Numeric.array([params[4:]])
+        indices = Numeric.array([params[0][:4]])
+        parameters = Numeric.array([params[0][4:]])
          return [CosineDihedralTerm(universe._spec, indices,  
parameters,
                                     self.name)]