spheropack.analysis.bond_order#

spheropack.analysis.bond_order(packing, l=6, cutoff=1.4)#

Bond-orientational order parameter of order l.

Two spheres are bonded when their distance is below cutoff * (r_i + r_j). The default 1.4 lies near the first minimum of g(r) of dense monodisperse packings.

In 3D this is Steinhardt’s Q_l. Reference values for perfect crystals with 12 nearest neighbours: FCC Q_4 = 0.191, Q_6 = 0.575; HCP Q_4 = 0.097, Q_6 = 0.485. In 2D it is the l-fold bond order |psi_l|, 1 for a perfect hexagonal crystal with l = 6.

Parameters:
Return type:

BondOrder