compute_R¶

sknano.core.structures.
compute_R
(*Ch, bond=None, length=False, **kwargs)[source] [edit on github][source]¶ Compute symmetry vector \(\mathbf{R} = (p, q)\).
The symmetry vector is any lattice vector of the unfolded graphene layer that represents a symmetry operation of the nanotube. The symmetry vector \(\mathbf{R}\) can be written as:
\[\mathbf{R} = p\mathbf{a}_1 + q\mathbf{a}_2\]where \(p\) and \(q\) are integers. The symmetry vector represents a symmetry operation of the nanotube which arises as a screw translation, which is 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 2tuple 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 carboncarbon bond length in graphite, approximately \(\mathrm{a}_{\mathrm{CC}} = 1.42\) Å
 length (bool, optional) – If
True
, return \(\mathbf{R}\).
Returns:  (p, q) (tuple) – 2tuple of ints – components of \(\mathbf{R}\).
 float –
Length of \(\mathbf{R}\) (\(\mathbf{R}\)) if
length
isTrue
in units of Å.
 *Ch –