title: Multiple environment single system quantum mechanical/molecular mechanical (MESS-QM/MM) calculations. 1. Estimation of polarization energies.
abstract: In combined quantum mechanical/molecular mechanical (QM/MM) free energy calculations, it is often advantageous to have a frozen geometry for the quantum mechanical (QM) region. For such multiple-environment single-system (MESS) cases, two schemes are proposed here for estimating the polarization energy: the first scheme, termed MESS-E, involves a Roothaan step extrapolation of the self-consistent field (SCF) energy; whereas the other scheme, termed MESS-H, employs a Newton-Raphson correction using an approximate inverse electronic Hessian of the QM region (which is constructed only once). Both schemes are extremely efficient, because the expensive Fock updates and SCF iterations in standard QM/MM calculations are completely avoided at each configuration. They produce reasonably accurate QM/MM polarization energies: MESS-E can predict the polarization energy within 0.25 kcal/mol in terms of the mean signed error for two of our test cases, solvated methanol and solvated β-alanine, using the M06-2X or ωB97X-D functionals; MESS-H can reproduce the polarization energy within 0.2 kcal/mol for these two cases and for the oxyluciferin-luciferase complex, if the approximate inverse electronic Hessians are constructed with sufficient accuracy.
authors.affiliation: Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health , 5635 Fishers Lane, T-900 Suite, Rockville, Maryland 20852, United States.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Sodt
authors.forename: Ye
authors.initials: Y
authors.lastname: Mei
authors.forename: Gerhard
authors.initials: G
authors.lastname: König
authors.forename: Peng
authors.initials: P
authors.lastname: Tao
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Steele
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Brooks
authors.forename: Yihan
authors.initials: Y
authors.lastname: Shao
mesh_terms: D000432:Methanol / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D015091:beta-Alanine / Q000737:chemistry*
chemical_list: D015091:beta-Alanine; D000432:Methanol