CASM file formats

These are quick links to descriptions of the most commonly used CASM project input and output files.

Note: A complete description of the CASM project directory structure with file locations is available here.

Name	Description	Format
basis.json	Basis set information	Basis Set
bspecs.json	Basis set specifications	Basis Set Specs
chemical_reference.json	Chemical reference states	Chemical Reference
clust.json	Cluster orbits information	Cluster Orbits
composition_axes.json	Composition axes definitions	Composition Axes
config.json	Configuration DoF values	Configuration
crystal_point_group.json	Crystal point group information	Symmetry Group
dof_space_<dof_type>.json	DoF-space analysis information	DoF Space
eci.json	Basis set with effective cluster interaction (ECI) values	Basis Set
factor_group.json	Prim factor group information	Symmetry Group
lattice_point_group.json	Lattice point group information	Symmetry Group
prim.json	Primitive crystal structure and allowed degrees of freedom (DoF)	Prim
project_settings.json	Project settings	Project Settings
properties.calc.json	Structure information with calculated properties	Structure
structure.json	Structure information	Structure

Additional documentation links

• CASM project directory structure
• JSON data formats
• Degrees of freedom (DoF) and properties
• Lattice canonical form

casm Python Packages

The casm namespace is used to distribute CASM Python packages (i.e. casm-python) that have pure Python implementations, though they may have libcasm package dependencies.

• casm Packages Overview
• Contributing to casm packages

libcasm Python Packages

The libcasm namespace is used to distribute CASM Python packages (i.e. libcasm-global, libcasm-xtal, etc.) that rely in some part on a C++ implementation.

• libcasm Packages Overview
• Contributing to libcasm packages

CASM v2+ transition

For CASM v2+, the large existing distributions CASMcode (for C++ code) and CASMpython are split into smaller distributions focused on particular topics. They are organized into two namespaces: libcasm, for packages that include C++ implementations, and casm, for pure Python packages.

Python namespace packages allow distributing subpackages seperately so a project may be split into smaller more focused efforts. For example, the CASM structure mapping package (libcasm.mapping) and the CASM cluster expansion Monte Carlo package (libcasm.clexmonte) can be developed and distributed separately. Each distribution package installs one or more Python namespace packages into the particular namespace.