  micrOMEGAs2.0 is a code which calculates the relic density of a stable
massive particle in an arbitrary model. The underlying assumption is that there
is a conservation law like R-parity in supersymmetry which guarantees the
stability of the lightest odd particle. The new physics model must be
incorporated in the notation of CalcHEP, a package for the automatic generation
of squared matrix elements. Once this is done, all annihilation and
coannihilation channels are included automatically in any model. Cross-sections
at $v=0$, relevant for indirect detection of dark matter, are also computed
automatically. The package includes three sample models: the minimal
supersymmetric standard model (MSSM), the MSSM with complex phases and the
NMSSM. Extension to other models, including non supersymmetric models, is
described.
