title: eReaxFF: A Pseudoclassical Treatment of Explicit Electrons within Reactive Force Field Simulations.
abstract: We present a computational tool, eReaxFF, for simulating explicit electrons within the framework of the standard ReaxFF reactive force field method. We treat electrons explicitly in a pseudoclassical manner that enables simulation several orders of magnitude faster than quantum chemistry (QC) methods, while retaining the ReaxFF transferability. We delineate here the fundamental concepts of the eReaxFF method and the integration of the Atom-condensed Kohn-Sham DFT approximated to second order (ACKS2) charge calculation scheme into the eReaxFF. We trained our force field to capture electron affinities (EA) of various species. As a proof-of-principle, we performed a set of molecular dynamics (MD) simulations with an explicit electron model for representative hydrocarbon radicals. We establish a good qualitative agreement of EAs of various species with experimental data, and MD simulations with eReaxFF agree well with the corresponding Ehrenfest dynamics simulations. The standard ReaxFF parameters available in the literature are transferrable to the eReaxFF method. The computationally economic eReaxFF method will be a useful tool for studying large-scale chemical and physical systems with explicit electrons as an alternative to computationally demanding QC methods.
authors.affiliation: Department of Mechanical and Nuclear Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Md Mahbubul
authors.initials: MM
authors.lastname: Islam
authors.affiliation: John A. Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Grigory
authors.initials: G
authors.lastname: Kolesov
authors.affiliation: Center for Molecular Modeling (CMM), Member of the QCMM Ghent-Brussels Alliance, Ghent University , Technologiepark 903, B9052 Zwijnaarde, Belgium.
authors.forename: Toon
authors.initials: T
authors.lastname: Verstraelen
authors.affiliation: John A. Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Efthimios
authors.initials: E
authors.lastname: Kaxiras
authors.affiliation: Department of Mechanical and Nuclear Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Adri C T
authors.initials: AC
authors.lastname: van Duin