Modulated Structures CIF Dictionary version 1.0

_atom_site_rot_Fourier_param_sin

Name

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)

Definition

    	
   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_sin is the sine
   coefficient (Rs) 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.