A charge equilibration formalism for treating charge transfer effects in MD simulations: Application to water clusters. Issue 16 (26th April 2017)

• Record Type: Journal Article
• Authors: Kumar Sinha, Sudipta; Mehta, Mohit; Patel, Sandeep
• Other Names: Hirst Jonathan guestEditor.; Im Wonpil guestEditor.; Shea Joan‐Emma guestEditor.
• Is Part Of: Journal of computational chemistry. Volume 38:Issue 16(2017)
• Page Start: 1389
• Page End: 1409
• Publication Date: 2017-04-26
• Subjects: charge transfer -- charge equilibration -- polarization -- force field -- molecular dynamics -- simulation; Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.24789
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract : Conventional classical force fields by construction do not explicitly partition intermolecular interactions to include polarization and charge transfer effects, whereas fully quantum mechanical treatments allow a means to effect this dissection (although not uniquely due to the lack of a charge transfer operator). Considering the importance of polarization in a variety of systems, a particular class of classical models, charge equilibration models, have been extensively developed to study those systems; since these types of interaction models are inherently based on movement of charge throughout a system, they are natural platform for including polarization and charge transfer effects within the context of molecular simulations. Here, we present two bond‐space charge equilibration models we term as QE2 and mixed QE2 treat charge transfer in classical molecular mechanical calculations those provide practical solutions to two major drawbacks of charge equilibration models: (a) a nonvanishing amount of charge transfer between two heteroatoms at large separations, and (b) superlinear polarizability scaling during bond dissociation due to charge transfer over unphysical, large distances. To control charge transfer during dissociation of a bond in a molecular system, we introduce a distance‐dependent scaling function (QE2 model) which, controls and recovers physical behavior of the homonuclear and heteronuclear charge transfer between two atoms at small and large values of internuclear separation; and the mixed QE2 model in which we combine the QE2 model under allow and disallow charge transfer situations that describe both charge transfer and polarizability in a distance‐dependent manner. We demonstrate the utility of both models in the case of a water dimer, and compare the results with other existing models, and further, we perform short molecular dynamics simulations for few water clusters with the QE2 model to show the charge transfer and internuclear separation are correlated in dynamics. © 2017 Wiley Periodicals, Inc. Abstract : Charge transfer in classical molecular dynamics simulations is modeled using a charge equilibration formalism. The distance dependence of charge transfer is modulated using a linear superposition of molecular topologies allowing and disallowing charge transfer at different spatial regimes.