Make NBFIX ordering consistent.

wrappers/python/simtk/openmm/app/charmmparameterset.py

@@ -446,10 +446,10 @@ class CharmmParameterSet(object):
                     except IndexError:
                         emin14 = rmin14 = None
                     try:
-                        self.atom_types_str[at1].add_nbfix(at2, emin, rmin,
-                                                           emin14, rmin14)
-                        self.atom_types_str[at2].add_nbfix(at1, emin, rmin,
-                                                           emin14, rmin14)
+                        self.atom_types_str[at1].add_nbfix(at2, rmin, emin,
+                                                           rmin14, emin14)
+                        self.atom_types_str[at2].add_nbfix(at1, rmin, emin,
+                                                           rmin14, emin14)
                     except KeyError:
                         # Some stream files define NBFIX terms with an atom that
                         # is defined in another toppar file that does not
@@ -460,7 +460,7 @@ class CharmmParameterSet(object):
                         pass
                 except IndexError:
                     raise CharmmFileError('Could not parse NBFIX terms.')
-                self.nbfix_types[(min(at1, at2), max(at1, at2))] = (emin, rmin)
+                self.nbfix_types[(min(at1, at2), max(at1, at2))] = (rmin, emin)
         # Now we're done. Load the nonbonded types into the relevant AtomType
         # instances. In order for this to work, all keys in nonbonded_types
         # must be in the self.atom_types_str dict. Raise a RuntimeError if this

wrappers/python/simtk/openmm/app/charmmpsffile.py

@@ -1294,7 +1294,7 @@ class CharmmPsfFile(object):
                 for j in range(num_lj_types):
                     namej = lj_type_list[j].name
                     try:
-                        wdij, rij, wdij14, rij14 = lj_type_list[i].nbfix[namej]
+                        rij, wdij, rij14, wdij14 = lj_type_list[i].nbfix[namej]
                     except KeyError:
                         rij = (lj_radii[i] + lj_radii[j]) * length_conv
                         wdij = sqrt(lj_depths[i] * lj_depths[j]) * ene_conv