The latest public release of
MOPAC (available to academics for free use from
http://openmopac.net/) newly
includes the INDO/S semiempirical Hamiltonian, which has parameters designed to
reproduce excited-state energies at the CIS level and can cheaply model states
with large double-excitation character using CISD or MRCI. The code also
includes COSMO solvent corrections, including state-specific excited-state
corrections for all INDO/CI approaches in the code.