Quantum IMOMM method

Matsubara T, Sieber S, Morokuma K (1996) A test of the new integrated MO + MM (IMOMM) method for the conformational energy of ethane and n-butane. Int J Quantum Chem 60 1101-1109... 

Quantum mechanical study of the photoisomerization reaction of PYP began with calculations of the adiabatic potential energy surfaces of small model compounds of the chromophore (Yamada et al. 2001). However, to fully describe the protein-chromophore interaction, we had to include the entire protein molecule in the photoisomerization reaction. Recently, QM/MM (Hayashi and Ohmine 2000) and the ONIOM (Yamada et al. 2002 Vreven and Morokuma 2003), both of which are hybrid methods of high- and low-level calculations, have been used for large molecular systems. We performed the ONIOM (IMOMM) calculations on PYP to elucidate the role of the protein enviroiunent (Yamada etal. 2004a,b). We also investigated the origin of the force that drives photoisomerization. 

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