nonbonded_interactions.py

## \example container/nonbonded_interactions.py
## This example shows how to set up an excluded volume restraint for a set of XYZRDecorator-style particles.

import IMP
import IMP.core
import IMP.atom
import IMP.container

# This example addes a restraint on nonbonded interactions
# after excluding a set of bonded interactions.

m= IMP.Model()
# The set of particles
ps = IMP.container.ListSingletonContainer(IMP.core.create_xyzr_particles(m, 20, 1.0))

# create a bond between two particles
bd0= IMP.atom.Bonded.setup_particle(ps.get_particle(0))
bd1= IMP.atom.Bonded.setup_particle(ps.get_particle(1))
IMP.atom.create_custom_bond(bd0, bd1, 2.0)

# Set up the nonbonded list for all pairs at are touching
# and let things move 3 before updating the list
nbl= IMP.container.ClosePairContainer(ps, 0.0, 3.0)
nbl.add_pair_filter(IMP.atom.BondedPairFilter())

# Set up excluded volume
sdps= IMP.core.SoftSpherePairScore(1)
evr= IMP.container.PairsRestraint(sdps, nbl)
m.add_restraint(evr)

# Set up optimizer
o= IMP.core.ConjugateGradients()
o.set_model(m)

o.optimize(1000)