Add point harmonic restraint#

Tethering atoms to target 3D Cartesian coordinates with harmonic positional restraints.

The function molsysmt.third_party.openmm.forces.add_point_harmonic_restraint() applies harmonic positional restraints to selected atoms relative to reference 3D coordinates.

Added in version 1.0.0.

API documentation

Follow this link for a detailed description of the input arguments, raised errors, and returned objects: molsysmt.third_party.openmm.forces.add_point_harmonic_restraint().

Basic usage#

Let’s add positional harmonic restraints to target coordinates:

import molsysmt as msm

molsys = msm.convert(msm.systems['Trp-Cage']['1l2y.h5msm'], to_form='molsysmt.MolSys')
force = msm.third_party.openmm.forces.add_point_harmonic_restraint(molsys, point='[0,0,0] nm', selection=[0], force_constant='1000 kJ/(mol*nm**2)', return_force=True)
print('Positional harmonic restraint created:', type(force))

Positional harmonic restraint created: <class 'openmm.openmm.CustomExternalForce'>