Alex A. Granovsky, Firefly version 7.1.G, www http://classic.chem.msu.su/gran/firefly/index.html
    the PC GAMESS version [1] of the GAMESS (US) QC package [2].
    Firefly QC package [1], which is partially based on the GAMESS (US) [2] source code.
    Alex A. Granovsky, Firefly version 7.1.G, www http://classic.chem.msu.su/gran/firefly/index.html
    M.W.Schmidt, K.K.Baldridge, J.A.Boatz, S.T.Elbert, M.S.Gordon, J.H.Jensen, S.Koseki, N.Matsunaga, K.A.Nguyen, S.Su, T.L.Windus, M.Dupuis, J.A.Montgomery J.Comput.Chem. 14, 1347-1363 (1993)