Increased default mass for Drude particles

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

@@ -805,7 +805,7 @@ class CharmmPsfFile(object):
                      flexibleConstraints=True,
                      verbose=False,
                      gbsaModel=None,
-                     drudeMass=0.1*u.amu):
+                     drudeMass=0.4*u.amu):
         """Construct an OpenMM System representing the topology described by the
         prmtop file. You MUST have loaded a parameter set into this PSF before
         calling createSystem. If not, AttributeError will be raised. ValueError
@@ -863,7 +863,7 @@ class CharmmPsfFile(object):
         gbsaModel : str=None
             Can be ACE (to use the ACE solvation model) or None. Other values
             raise a ValueError
-        drudeMass : mass=0.1*amu
+        drudeMass : mass=0.4*amu
             The mass to use for Drude particles.  Any mass added to a Drude particle is
             subtracted from its parent atom to keep their total mass the same.
         """

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

@@ -1082,7 +1082,7 @@ class ForceField(object):
 
     def createSystem(self, topology, nonbondedMethod=NoCutoff, nonbondedCutoff=1.0*unit.nanometer,
                      constraints=None, rigidWater=None, removeCMMotion=True, hydrogenMass=None, residueTemplates=dict(),
-                     ignoreExternalBonds=False, switchDistance=None, flexibleConstraints=False, drudeMass=0.1*unit.amu, **args):
+                     ignoreExternalBonds=False, switchDistance=None, flexibleConstraints=False, drudeMass=0.4*unit.amu, **args):
         """Construct an OpenMM System representing a Topology with this force field.
 
         Parameters
@@ -1124,7 +1124,7 @@ class ForceField(object):
             Lennard-Jones interactions. If this is None, no switching function will be used.
         flexibleConstraints : boolean=False
             If True, parameters for constrained degrees of freedom will be added to the System
-        drudeMass : mass=0.1*amu
+        drudeMass : mass=0.4*amu
             The mass to use for Drude particles.  Any mass added to a Drude particle is
             subtracted from its parent atom to keep their total mass the same.
         args