title: Influence of Coupling and Embedding Schemes on QM Size Convergence in QM/MM Approaches for the Example of a Proton Transfer in DNA.
abstract: The influence of embedding and coupling schemes on the convergence of the QM size in the QM/MM approach is investigated for the transfer of a proton in a DNA base pair. We find that the embedding scheme (mechanical or electrostatic) has a much greater impact on the convergence behavior than the coupling scheme (additive QM/MM or subtractive ONIOM). To achieve size convergence, QM regions with up to 6000 atoms are necessary for pure QM or mechanical embedding. In contrast, electrostatic embedding converges faster: for the example of the transfer of a proton between DNA base pairs, we recommend including at least five base pairs and 5 Å of solvent (including counterions) into the QM region, i.e., a total of 1150 atoms.
authors.affiliation: Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU Munich) , Butenandtstr. 7, D-81377 Munich, Germany.|Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry, University of Munich (LMU Munich) , Butenandtstr, 5-13, D-81377 Munich, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Roßbach
authors.affiliation: Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU Munich) , Butenandtstr. 7, D-81377 Munich, Germany.|Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry, University of Munich (LMU Munich) , Butenandtstr, 5-13, D-81377 Munich, Germany.
authors.forename: Christian
authors.identifier: http://orcid.org/0000-0002-4189-6558
authors.initials: C
authors.lastname: Ochsenfeld
mesh_terms: D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011522:Protons; D011789:Quantum Theory; D055672:Static Electricity
chemical_list: D011522:Protons; D004247:DNA