Electron density dictionary (rhoCIF) version 1.0.1

_atom_local_axes_ax1

Definition:

   Specifies 'ax1' in the definition of a local axis frame.
   The definition employs three atom-site labels, 'atom0', 'atom1'
   and 'atom2', and two axis labels, 'ax1' and 'ax2', having values
   '+/-X', '+/-Y' or '+/-Z'. For the atom defined by
   '_atom_local_axes_atom_label', whose nuclear position is taken
   as the origin, local axis 'ax1' is the vector from the origin to
   atom0, axis 'ax2' is perpendicular to 'ax1' and lies in the
   plane of 'ax1' and a vector
   passing through the origin parallel to the vector atom1 -> atom2
   (its positive direction making an acute angle with the vector
   parallel to atom1 -> atom2), and a right-handed orthonormal
   vector triplet is formed from the vector product of these two
   vectors. In most cases, atom1 will be the same as the atom
   specified by _atom_local_axes_atom_label. One or more 'dummy'
   atoms (with arbitrary labels) may be used in the vector
   definitions, specified with zero occupancy in the _atom_site_
   description.  The values of *_atom0, *_atom1 and *_atom2 must
   be identical to values given in the _atom_site_label list.

Appears in list containing _atom_local_axes_atom_label

Type: char

Category: atom_local_axes