compute_symmetry_operation

sknano.core.structures.compute_symmetry_operation(*Ch, bond=None)

Compute symmetry operation $(\psi|\tau)$.

The symmetry vector R represents a symmetry operation of the nanotube which arises as a screw translation–a combination of a rotation $\psi$ and translation $\tau$. The symmetry operation of the nanotube can be written as:

$$R = (\psi|\tau)$$

Parameters:

• *Ch –

  Either a 2-tuple of ints or 2 integers giving the chiral indices of the nanotube chiral vector $\mathbf{C}_h = n\mathbf{a}_1 + m\mathbf{a}_2 = (n, m)$.

• bond (float, optional) – Distance between nearest neighbor atoms (i.e., bond length). Must be in units of Å. Default value is the carbon-carbon bond length in graphite, approximately $\mathrm{a}_{\mathrm{CC}} = 1.42$ Å

Returns:

(psi, tau) – 2-tuple of floats – $\psi$ in radians and $\tau$ in Å.

Return type:

tuple