calculate dipole moment

dipole.py

import mdtraj as md
import numpy as np

def dipole_moment(traj, charges):
    """Compute the dipole moment of an MDTraj object."""
    xyz = md.compute_displacements(traj, np.array([[0, i] for i in range(traj.n_atoms)])).astype('float')
    return xyz.transpose(0, 2, 1).dot(charges)