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Modulated and composite structures dictionary (msCIF) version 1.0.1

_atom_site_displace_Fourier_param_modulus

Name:
'_atom_site_displace_Fourier_param_modulus'

Definition:

   The displacive distortion of a given atom or rigid group (see
   also _atom_site_rot_Fourier_param_modulus) is usually
   parameterized by Fourier series. Each term of the series commonly
   adopts two different representations: the sine-cosine form,
            Ac cos(2\p k r)+As sin(2\p k r),
   and the modulus-argument form,
            |A| cos(2\p k r+\f),
   where k is the wave vector of the term and r is the atomic
   average position. _atom_site_displace_Fourier_param_modulus is
   the modulus (|A|) of the complex amplitude corresponding to the
   Fourier term defined by
   _atom_site_displace_Fourier_atom_site_label,
   _atom_site_displace_Fourier_axis and
   _atom_site_displace_Fourier_wave_vector_seq_id. Atomic or rigid-
   group displacements must be expressed as fractions of the unit
   cell or in angstroms if the modulations are referred to some
   special axes defined by
   _atom_sites_displace_Fourier_axes_description.

Appears in list containing _atom_site_displace_Fourier_param_id
The permitted range is 0.0 -> infinity
Enumeration default: 0.0

Type: numb

Category: atom_site_displace_Fourier_param