MD++ is a molecular dynamics simulation package written in C++. It is originally developed by Wei Cai when he was a graduate student at MIT and still being updated to include more features. It features a flexible input language and an interactive 3D viewer.

Fe example
Defects emitting from crack tips in BCC Fe loaded in tension. Snapshot taken from running test case: bin/fs_gpp MD++/scripts/Examples/example01b-fe-crack.script