Yet Another Dynamic Engine (YADE) is an extensible framework that is designed with dynamic libraries in a way that it is easy to add new numerical models and objects. There are four different models: Discrete Element Method based on spheres, a second method based on tetrahedra, modelling with lattice elements, and Finite Element Method.
Cadabra is a computer algebra system designed specifically for the solution of problems encountered in field theory. It has extensive functionality for tensor polynomial simplification including multi-term symmetries, fermions and anti-commuting variables, Clifford algebras and Fierz transformations, implicit coordinate dependence, multiple index types, and many more. The input format is a subset of TeX. Both a command-line and a graphical interface are available.
Debyer takes a file with atom positions as input and can output X-ray and neutron diffraction patterns, the total scattering structure function, the pair distribution function (PDF), and related functions (RDF, reduced PDF). It can be used for comparison of molecular dynamics simulations or other models of atomistic structure of the material with X-ray and neutron powder diffraction experiments. The parallel version uses the MPI library.
EXODUS II is a model developed to store and retrieve finite element geometry, topology, and transient data for finite element analyses. It is used for preprocessing, postprocessing, as well as code to code data transfer. ExodusII is based on netcdf. It includes the nemesis parallel extension.
Extrema, originally developed in the fields of nuclear and particle physics, is a powerful visualization and data analysis tool that enables researchers to quickly distill their large, complex data sets into meaningful information. Its flexibility, sophistication, and power allow you to easily develop your own commands and create highly customized graphs.
The FOX (Free Objects for Crystallography) program is made for determining crystal structure ab initio from diffraction data (mostly powder diffraction). It is built on an object-oriented crystallographic computing library called ObjCryst++. FOX features a graphical interface, including a 3D OpenGL display of the crystal structure. It provides a versatile description of the crystal structures (such as atoms, molecules, and polyhedra). Special positions and overlapping atoms are automatically handled without any a priori knowledge.