A QM/MD coupling method to model the ion-induced polarization of graphene

Abstract

We report a new Quantum Mechanical/Molecular Dynamics (QM/MD) simulation loop to model the coupling between the electron and atom dynamics in solid/liquid interfacial systems. The method can describe simultaneously both the quantum mechanical surface polarizability emerging from the proximity to the electrolyte, and the electrolyte structure and dynamics. In the current set up Density Functional Tight Binding calculations for the electronic structure calculations of the surface are coupled with classical molecular dynamics to simulate the electrolyte solution. The reduced computational cost of the QM part makes the coupling with a classical simulation engine computationally feasible and allows simulation of large systems for hundreds of nanoseconds. We tested the method by simulating both a non-charged graphene flake and a non-charged and charged infinite graphene sheet immersed in an NaCl electrolyte solution. We found that, when no bias is applied, ions preferentially remained in solution and only cations are mildly attracted to the surface of the graphene. This preferential adsorption of cations vs anions seems to persist also when the surface is moderately charged and rules out any substantial ions/surface charge transfer.

arXiv comment22 pages, 8 figures

References in corpus (9)

• Lithium Diffusion in Graphitic Carbon
• Density-functional tight-binding for beginners
• Friction of Water on Graphene and Hexagonal Boron Nitride from ab initio Methods: Very Different Slippage Despite Very Similar Interface Structures
• Evaluation of Constant Potential Method in Simulating Electric Double-Layer Capacitors
• Polarizable ions at interfaces
• Tunable bandgap and magnetic ordering by adsorption of molecules on graphene
• On the physisorption of water on graphene: Sub-chemical accuracy from many-body electronic structure methods
• Graphene nanoflakes - structural and electronic properties
• Second order optical nonlinearity of graphene due to electric quadrupole and magnetic dipole effects

Cited by in corpus (5)

• Constant Chemical Potential-Quantum Mechanical-Molecular Dynamics simulations of the Graphene-electrolyte double layer
• Deriving effective electrode-ion interactions from free-energy profiles at electrochemical interfaces
• Electrochemistry, Ion Adsorption and Dynamics in the Double Layer: A Study of NaCl(aq) on Graphite
• Cation Dominated but Negatively Charged Na2SO4,aq-Graphene Interfaces
• Brownian dynamics simulations of electric double-layer capacitors with tunable metallicity