Category: atom_site_rot_Fourier_param
Data type: numb (with optional s.u. in parentheses)
Must appear in a looped list
containing '_atom_site_rot_Fourier_param_id'
Enumeration default: 0.0
Units: 'deg' ( Degrees)
The displacive distortion of a given rigid group is not completely described by _atom_site_displace_Fourier_. The rigid rotation of the group around a given axis passing through a fixed point (for example the centre of mass of the group) is usually parameterized by Fourier series. Each term of the series commonly adopts two different representations: the sine-cosine form, Rc cos(2\p k r)+Rs sin(2\p k r); and the modulus-argument form, |R| cos(2\p k r+\y); where k is the wave vector of the term and r is the atomic average position. _atom_site_rot_Fourier_param_cos is the cosine coefficient (Rc) in degrees, corresponding to the Fourier term defined by _atom_site_rot_Fourier_atom_site_label, _atom_site_rot_Fourier_axis, and _atom_site_rot_Fourier_wave_vector_seq_id.