title: Hybrid RHF/MP2 geometry optimizations with the effective fragment molecular orbital method.
abstract: The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile. For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two.
authors.affiliation: Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Anders S
authors.initials: AS
authors.lastname: Christensen
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark.
authors.forename: Casper
authors.initials: C
authors.lastname: Steinmann
authors.affiliation: Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan.
authors.forename: Dmitri G
authors.initials: DG
authors.lastname: Fedorov
authors.affiliation: Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jan H
authors.initials: JH
authors.lastname: Jensen
mesh_terms: D008958:Models, Molecular; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D011506:Proteins