"Coupling DFT to polarizable force fields for efficient and accurate Hamiltonian molecular dynamics simulations" Magnus Schwörer, Benedikt Breitenfeld, Philipp Tröster, Sebastian Bauer, Konstantin Lorenzen, Paul Tavan, and Gerald Mathias
J. Chem. Phys. 138, 244103 (2013)
Abstract: Hybrid molecular dynamics (MD) simulations, in which the forces acting on the atoms are calculated by gridbased density functional theory (DFT) for a solute molecule and by a polarizable molecular mechanics (PMM) force field for a large solvent environment composed of several 10^{3}10^{5} molecules, pose a challenge. A corresponding computational approach should guarantee energy conservation, exclude articial distortions of the electron density at the interface between the DFT and
PMM fragments, and should treat the longrange electrostatic interactions within the hybrid simulation system in a linearly scaling fashion. Here we describe a corresponding Hamiltonian DFT/(P)MM implementation, which accounts for inducible atomic dipoles of a PMM environment in a joint DFT/PMM selfconsistency iteration. The longrange parts of the electrostatics are treated by hierarchically nested fast multipole expansions up to a maximum distance dictated by the minimum image convention of toroidal boundary conditions and, beyond that distance, by a reaction field approach such that the computation scales linearly with the number of PMM atoms. Shortrange overpolarization artifacts are excluded by using Gaussian inducible dipoles throughout the system and Gaussian partial charges in the PMM region close to the DFT fragment. The Hamiltonian character, the stability and effieciency of the implementation are investigated by hybrid DFT/PMMMD simulations
treating one molecule of the water dimer and of bulk water by DFT and the respective remainder by PMM.
BMO authors (in alphabetic order): Sebastian Bauer Konstantin Lorenzen Gerald Mathias Magnus Schwörer Paul Tavan Philipp Troester
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