Index

Modulated structures dictionary (msCIF) version 3.2.1

_atom_site_rot_special_func.sawtooth

Definition:

   

      _atom_site_rot_special_func.sawtooth_ items are the
      adjustable parameters of a sawtooth function.
      A rotational sawtooth function along the internal space is
      defined as follows:

         [rx, ry, rz] = 2* [ax, ay, az] * ((x4-c)/w)

      for x4 belonging to the interval [c-(w/2), c+(w/2)], where ax,
      ay and az are the amplitudes (maximum displacements)
      along each axis, w is its width, x4 is the
      internal coordinate and c is the centre of the function in
      internal space. rx, ry and rz must be expressed in degrees.
      Special axes are defined by the items belonging to the ATOM_SITES_AXES 
      category, through _atom_site_rot_special_func.matrix_seq_id.

      The use of this function is restricted to one-dimensional 
      modulated structures. For more details, see the manual for
      JANA2006 (Petricek, Dusek & Palatinus, 2014) and (Petricek, Eigner, 
      Dusek & Cejchan, 2016). In the case of rigid groups, items in this 
      category would only include the rotational part of the modulation. 
      The translationalional part would appear in a separate list of items belonging 
      to the ATOM_SITE_DISPLACE_SPECIAL_FUNC category.

      References: Petricek, V., Dusek, M. & Palatinus, L. (2014).
              Z. Kristallogr. 229(5), 345-352.  DOI 10.1515/zkri-2014-1737     
              Crystallographic Computing System JANA2006: General features

              Petricek, V., Eigner, V., Dusek, M. & Cejchan, A. (2016). Z.                      
              Kristallogr. 231(5), 301-312. DOI 10.1515/zkri-2015-1913 
              Discontinuous modulation functions and their application for 
              analysis of modulated structures with the computing system JANA2006

Type: Real

Values appear in Matrix context.

Dimension: [3]

Evaluation method:

      With  f  as  atom_site_rot_special_func

      atom_site_rot_special_func.sawtooth =  [
          
         2 * [sawtooth_ax, sawtooth_ay, sawtooth_az] * 
                     (( sawtooth_x4 - sawtooth_c) / sawtooth_w )]

Category:
atom_site_rot_special_func