Campos ASE is an Atomistic Simulation Environment written in the python programming language with the aim of setting up, stearing, and analyzing atomistic simulations. The ASE has been constructed with a number of "design goals" as:

Simplicity in use.
Setting up an atomistic total energy calculation or molecular dynamics simulation with ASE is simple and straightforward. The python scripts are almost self-explanatory and look like well commented input files to an atomistic simulation program.
Flexibility in use.
Since ASE is based on the python scripting language it is possible without any code modifications to perform very complicated simulation tasks. For example a sequence of calculations may be performed with the use of simple "for-loop" constructions or simulations of different types (DFT and classical molecular dynamics) may be coupled together.
Simplicity in development
The ASE defines a set of interfaces for different objects, i.e. an "atom" object is required to posses a method with the name "GetCartesianPosition" which returns the Cartesian coordinates of the atom. By following a few such standard interfaces it is easy for new users to get access to all of the functionality of ASE.
Flexibility in development
The python code in ASE is structured in different modules intended for different purposes. There are "DFT-calculators" for performing DFT calculations, "dynamics" for controlling the motion of atoms, "filters" for constraining motion or performing nudged-elastic-band calculations etc. The modularity of the code and the documented interfaces make it simple to contribute new functionality to ASE.
Open to participation
All of the code in ASE is carrying the GNU General Public License and people are invited to participate in using and developing the code.