FINDSYM Help

Harold T. Stokes, Branton J. Campbell, and Dorian M. Hatch, Department of Physics and Astronomy, Brigham Young University, Provo, Utah, 84602, USA, stokesh@byu.edu

FINDSYM identifies the space group of a crystal, given the positions of the atoms in a unit cell.

Sample input: NaCl

Input:

(1) title line. This line is copied to the output, but is otherwise ignored by the program.

(2) tolerance. This is the accuracy to which dimensions of the unit cell and positions of atoms are known. Units should be the same as those used for the lattice parameters (usually Angstroms). If zero is entered, the default value of 1.0d-6 will be used.

(3a) lattice parameters: a,b,c,alpha,beta,gamma. Give the angles, alpha, beta, gamma, in degrees.

(3b) lattice vectors in cartesian coordinates. If anything is entered in this field, the program will use these lattice vectors instead of the lattice parameters above. If nothing is entered in this field, the program will use the lattice parameters above.

(4) known centering: P (no known centering), I (body-centered), F (face-centered), A,B,C (base centered), R (rhombohedral centered with coordinates of centered points at (2/3,1/3,1/3) and (1/3,2/3,2/3)).

(5) setting in International Tables for Crystallography. (a) monoclinic axes (unique axis in parentheses), (b) cell choice 1, 2, or 3 (for centered monoclinic), (c) orthorhombic axes, (d) origin choice 1 or 2, (e) hexagonal or rhombohedral axes (for trigonal). See Table 4.3.1 in International Tables for Crystallography for more information about monoclinic and orthorhombic axes.

(6) number of atoms. Enter the number of atoms in the known primitive unit cell.

(7) types of atoms. Give the chemical symbol (Na, Cl, etc.) for each atom. The symbol may contain information about net charge (Fe+2,Fe+3,...) or any other characteristic which may distinguish two atomic sites so that a symmetry operation that takes one atom into the other would be forbidden.

You may use multipliers for entering multiple number of atoms of the same type (for example, 2*Na for Na Na).

(8) include magnetic moments. Check if any atoms have magnetic moments.

(9) positions of atoms. Enter the dimensionless coordinates of each atom (fractions of a,b,c). If "include magnetic moments" is checked above, enter the components mx,my,mz, of the magnetic moments for each atom following the coordinates of its position (even if the magnetic moment of that atom is zero).

Output:

(1) space group identified by

(2) CIF file for resulting structure

(3) link to ISOCIF rendition of unit cell