LibRASSF can be enabled by setting EXCHANGE = HF, CORRELATION = RASCI2, and LIBRASSF = 1 in the $rem variable section. One should also indicate the number of roots by setting RAS_N_ROOTS appropriately. Although the module is called through RASCI2, most job control options are more similar to those found in RASCI1, with the exception of RAS_N_ROOTS.
The number of spin-flips and IP/EA are determined by the $rem variables RASSF_DELTA_ALPHA (the number of alpha electrons removed) and RASSF_DELTA_BETA (the number of beta electrons added). Hole and particle excitations can be added by setting the DO_HOLE and DO_PARTICLE keywords. Additionally, text files containing eigenvalues and eigenvectors can be printed via the RASSF_WRITE_EVALS and RASSF_WRITE_EVECS keywords.