Modulated Structures CIF Dictionary version 1.0

_atom_site_occ_Fourier_param_cos

Name

Category: atom_site_occ_Fourier_param

Data type: numb (with optional s.u. in parentheses)

Must appear in a looped list containing '_atom_site_occ_Fourier_param_id'
Enumeration default: 0.0

Definition

    	
   The occupational distortion of a given atom or rigid group is
   usually parameterized by Fourier series. Each term of the series
   commonly adopts two different representations: the sine-cosine
   form,
            Pc cos(2\p k r)+Ps sin(2\p k r);
   and the modulus-argument form,
            |P| cos(2\p k r+\d);
   where k is the wave vector of the term and r is the atomic
   average position. _atom_site_occ_Fourier_param_cos is the cosine
   coefficient (Pc) corresponding to the Fourier term defined by
   _atom_site_occ_Fourier_atom_site_label, and
   _atom_site_occ_Fourier_wave_vector_seq_id.