Input file format

When using the -f switch, the input file for the findsym program has to be given. This file specifies the crystal and the magnetic structure.

Note that magnetic mode always has to be used, even if the structure is non-magnetic. Simply specify the magnetic moments as zero.

The file has to have the following format, as described in findsym documentation:

Input file format

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

  2. tolerance: 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 in (4) below. If zero is entered, the default value of 1.0d-6 will be used.

  3. form of lattice parameters. Form 1 indicates lattice parameters will be entered as 3 vectors, and form 2 indicates lattice parameters will be given in terms of lengths and angles. This allows two different ways of entering this data.

  4. lattice parameters. If form 1 is given, then enter the cartesian coordinates of the three vectors that define the conventional unit cell. Enter each vector on a separate line. If form 2 is given, then enter a,b,c,alpha,beta,gamma. Give the angles, alpha,beta,gamma, in degrees.

  5. form of basis vectors of unit cell. Form 1 indicates basis vectors will be entered as three dimensionless vectors, and form 2 indicates that a label for the centering will be given.

  6. basis vectors of the unit cell.

Form 1: Enter the basis vectors of the lattice which defines the unit cell. This unit cell does not need to be primitive. The vectors should be given in terms of the basis vectors of the conventional lattice defined in (6). Enter each vector on a separate line. These vector components are dimensionless and must be accurate to 3 decimal places. For example, 1/2 would be entered as 0.5, and 1/3 would be entered as 0.333. If the unit cell is the same as the conventional unit cell, enter 1,0,0, 0,1,0, and 0,0,1.

Form 2: Enter the known centering of the unit cell: P (primitive or no known centering), I (body-centered), F (face-centered), A,B,C (base centered), or R (rhombohedral centered with coordinates of centered points at (2/3,1/3,1/3) and (1/3,2/3,2/3), the convention used in International Tables of Crystallography).

  1. number of atoms. Enter the number of atoms in the unit cell defined in (6).

  2. types of atoms. Enter the symbol for each type of atom, one for each atom in the unit cell defined in (6). These symbols may simply be integers (1,2,3…) or actual chemical symbols (Na,Cl…). 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.

  3. magnetic. Enter the word, “magnetic,” on this line if atoms in the structure have magnetic moments.

  4. positions of atoms. Enter the coordinates of each atom in the unit cell defined in (6). Give the coordinates in terms of the basis vectors of the conventional lattice defined in (4). These coordinates are dimensionless. Enter the coordinates of each atom on a separate line.

If some atoms have magnetic moments, then enter those on the same line as the coordinates of their positions. Enter the magnetic moment for every atom, even for those with no magnetic moment. Give the components of the magnetic moment along the basis vectors of the conventional lattice defines in (4).

  1. settings in the Internation Tables for Crystallography (optional). This specifies the setting to be used for the space group in the output. For each setting desired, enter the command given in the first column below, each command on a separate line.

    axis b unique axis b for monoclinic space groups (default) axis c unique axis b for monoclinic space groups cell 1 cell choice 1 for centered monoclinic space groups (default) cell 2 cell choice 2 for centered monoclinic space groups cell 3 cell choice 3 for centered monoclinic space groups origin 1 origin choice 1 (when point of inversion is not at origin) origin 2 origin choice 2 (point of inversion at origin, default) axes h hexagonal axes for R-centered space groups (default) axes r rhombohedral axes for R-centered space groups

Example of the input file:

Mn2Au
0.001
2
3 3 8 90 90 90
2
I
3
Mn Mn Au
magnetic
0 0 0.333333 1 0 0
0 0 0.666667 -1 0 0
0 0 0 0 0 0

Further examples of the input file can be found in the tests/ <https://bitbucket.org/zeleznyj/linear-response-symmetry/src/master/tests/> directory.