FINDSYM identifies the space group of a crystal, given the positions of the atoms in a unit cell.
Input:
(1) title line. This line is copied to the output, but is otherwise ignored by the program.
(2) accuracy to be used in comparing two numbers. If zero is entered, the default value of 1.0d-6 will be used.
(3) lattice parameters: a,b,c,alpha,beta,gamma. Give the angles, alpha, beta, gamma, in degrees.
(4) basis vectors of the unit cell. Enter the basis vectors of the lattice which defines the unit cell. This unit cell may or may not be primitive. The vectors should be given in dimensionless units in terms of the basis vectors of the conventional lattice defined in (3). If the unit cell is the same as the conventional unit cell, enter 1,0,0, 0,1,0, and 0,0,1.
(5) number of atoms. Enter the number of atoms in the unit cell defined in (4).
(6) types of atoms. Assign each type to an arbitrary positive integer. Enter these integers, one for each atom in the unit cell defined in (4). Type may refer to chemical identity (Mg,Na,F,etc.) or net charge (Fe+2,Fe+3,...) or any other characteristic which may distinguish two atoms so that a symmetry operation that takes one atom into the other would be forbidden.
(7) positions of atoms. Enter the coordinates of each atom in the unit cell defined in (4). Give the coordinates in terms of the basis vectors of the conventional lattice defined in (3). These coordinates are dimensionless.
Output:
(1) additional lattice points in the unit cell.
(2) basis vectors of the primitive lattice.
(3) space-group elements.
(4) space group identified by
(b) origin of the space group with respect to the origin in the input data. Coordinates are dimensionless, given in terms of the basis vectors of the conventional unit cell in the input.
(c) basis vectors of the conventional unit cell defined in International Tables of Crystallography. Components are dimensionless, given in terms of the basis vectors of the conventional unit cell in the input.
(d) lattice parameters a,b,c,alpha,beta,gamma for the basis vectors given in (c).
(e) atomic positions grouped by Wyckoff position. Coordinates are dimensionless, given in terms of the conventional unit cell defined in International Tables of Crystallography. These correspond exactly to the form of the Wyckoff positions given in International Tables of Crystallography.
FINDSYM uses the following settings of space groups in International Tables of Crystallography:
monoclinic: unique axis b, cell choice 1
rhombohedral: hexagonal axes
origin choice 2 (point of inversion at origin)