A suite of vibrational multi-reference methods is available now. Modals can be optimized at the VMCSCF level
[S. Heislbetz and G. Rauhut, J. Chem. Phys. 132, 124102 (2012)] and
correlation effects can be accounted for either variationally (VMRCI
[F. Pfeiffer and G. Rauhut, J. Chem. Phys. 140, 064110 (2014)].