title: Toward Hamiltonian Adaptive QM/MM: Accurate Solvent Structures Using Many-Body Potentials.
abstract: Adaptive quantum mechanical (QM)/molecular mechanical (MM) methods enable efficient molecular simulations of chemistry in solution. Reactive subregions are modeled with an accurate QM potential energy expression while the rest of the system is described in a more approximate manner (MM). As solvent molecules diffuse in and out of the reactive region, they are gradually included into (and excluded from) the QM expression. It would be desirable to model such a system with a single adaptive Hamiltonian, but thus far this has resulted in distorted structures at the boundary between the two regions. Solving this long outstanding problem will allow microcanonical adaptive QM/MM simulations that can be used to obtain vibrational spectra and dynamical properties. The difficulty lies in the complex QM potential energy expression, with a many-body expansion that contains higher order terms. Here, we outline a Hamiltonian adaptive multiscale scheme within the framework of many-body potentials. The adaptive expressions are entirely general, and complementary to all standard (nonadaptive) QM/MM embedding schemes available. We demonstrate the merit of our approach on a molecular system defined by two different MM potentials (MM/MM'). For the long-range interactions a numerical scheme is used (particle mesh Ewald), which yields energy expressions that are many-body in nature. Our Hamiltonian approach is the first to provide both energy conservation and the correct solvent structure everywhere in this system.
authors.affiliation: Inorganic Chemistry and Catalysis group, Debye Institute for Nanomaterials Science, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Jelle M
authors.initials: JM
authors.lastname: Boereboom
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Raffaello
authors.initials: R
authors.lastname: Potestio
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.|Department of Chemistry, University of California Davis , One Shields Avenue, Davis, California 95616, United States.|Donostia International Physics Center, Paseo Manuel de Lardizabal, 4, E-20018 Donostia-San Sebastian, Spain.|IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain.
authors.forename: Davide
authors.initials: D
authors.lastname: Donadio
authors.affiliation: Inorganic Chemistry and Catalysis group, Debye Institute for Nanomaterials Science, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Rosa E
authors.initials: RE
authors.lastname: Bulo