# ISOTROPY Software Suite

Harold T. Stokes, Dorian M. Hatch, and Branton J. Campbell,
Department of Physics and Astronomy,
Brigham Young University, Provo, Utah 84606, USA, stokesh@byu.edu

**Description**:
The ISOTROPY software suite
is a collection of software which applies group theoretical
methods to the analysis of phase transitions in crystalline solids.

**How to cite**: ISOTROPY Software Suite, iso.byu.edu.

### Isotropy subgroups and distortions

**ISODISTORT**: Explore and
visualize distortions of crystalline structures. Possible distortions
include atomic displacements, atomic ordering, strain, and magnetic
moments.
**ISOSUBGROUP**:
Interactive program using user-friendly interface to list isotropy subgroups.
**ISOTROPY**:
Interactive program using command lines to explore isotropy subgroups
and their associated distortions.
**SMODES**:
Find the displacement modes in
a crystal which brings the dynamical matrix to block-diagonal form,
with the smallest possible blocks.
**FROZSL**:
Calculate phonon frequencies
and displacement modes using the method of frozen phonons.

### Space groups and irreducible representations

**ISOCIF**:
Create or modify CIF files.
**FINDSYM**:
Identify the space group of a
crystal, given the positions of the atoms in a unit cell.
**ISO-IR**:
Tables of Irreducible Representations. The 2011 version of IR matrices.
**ISO-MAG**:
Tables of magnetic space groups, both in human-readable and computer-readable forms.

### Superspace Groups

**ISO(3+d)D**:
(3+d)-Dimensional Superspace Groups for d=1,2,3
**ISO(3+1)D**:
Isotropy Subgroups for
Incommensurately Modulated Distortions in Crystalline Solids:
A Complete List for One-Dimensional Modulations
**FINDSSG**:
Identify the superspace group
symmetry given a list of symmetry operators.
**TRANSFORMSSG**:
Transform a superspace
group to a new setting.

### Phase Transitions

**COPL**:
Find a complete list of order parameters
for a phase transition, given the space-group symmetries of the parent and
subgroup phases.
**INVARIANTS**:
Generate invariant
polynomials of the components of order parameters.
**COMSUBS**:
Find common subgroups of two
structures in a reconstructive phase transition

### Linux