MOLCAS is an ab initio computational chemistry program, developed as a joint project by a number of international institutes.

It is not primarily a commercial product and it is not sold in order to produce a fortune for its owner (the Lund University).

Focus in the program is placed on methods for calculating general electronic structures in both ground and excited states.

MOLCAS contains codes for general and effective multiconfigurational SCF calculations at the Complete Active Space (CASSCF) level, but also employing more restricted MCSCF wave functions (RASSCF).

It is also possible, at this level of theory, to optimize geometries for equilibrium and transition states using gradient techniques and to compute force fields and vibrational energies.