Toward Accurate Adsorption Energetics on Clay Surfaces

Abstract

Clay minerals are ubiquitous in nature, and the manner in which they interact with their surroundings has important industrial and environmental implications. Consequently, a molecular-level understanding of the adsorption of molecules on clay surfaces is crucial. In this regard computer simulations play an important role, yet the accuracy of widely used empirical force fields (FF) and density functional theory (DFT) exchange-correlation functionals is often unclear in adsorption systems dominated by weak interactions. Herein we present results from quantum Monte Carlo (QMC) for water and methanol adsorption on the prototypical clay kaolinite. To the best of our knowledge, this is the first time QMC has been used to investigate adsorption at a complex, natural surface such as a clay. As well as being valuable in their own right, the QMC benchmarks obtained provide reference data against which the performance of cheaper DFT methods can be tested. Indeed using various DFT exchange-correlation functionals yields a very broad range of adsorption energies, and it is unclear a priori which evaluation is better. QMC reveals that in the systems considered here it is essential to account for van der Waals (vdW) dispersion forces since this alters both the absolute and relative adsorption energies of water and methanol. We show, via FF simulations, that incorrect relative energies can lead to significant changes in the interfacial densities of water and methanol solutions at the kaolinite interface. Despite the clear improvements offered by the vdW-corrected and the vdW-inclusive functionals, absolute adsorption energies are often overestimated, suggesting that the treatment of vdW forces in DFT is not yet a solved problem.

in J. Phys. Chem. C, (2016)

References in corpus (13)

• A Higher-Accuracy van der Waals Density Functional
• Perspective: Advances and challenges in treating van der Waals dispersion forces in density functional theory
• A molecular perspective of water at metal interfaces
• Continuum variational and diffusion quantum Monte Carlo calculations
• The role of van der Waals forces in water adsorption on metals
• The Finite Size Error in Many-body Simulations with long-Ranged Interactions
• To wet or not to wet? Dispersion forces tip the balance for water-ice on metals
• Finite-size correction in many-body electronic structure calculations
• Unexpectedly high pressure for molecular dissociation in liquid hydrogen by a reliable electronic simulation
• Water on hexagonal boron nitride from diffusion Monte Carlo
• Ab-initio molecular dynamics simulation of liquid water by Quantum Monte Carlo
• Distinct metallization and atomization transitions in dense liquid hydrogen
• Ab Initio Many-body Study of Cobalt Adatoms Adsorbed on Graphene

Cited by in corpus (1)

• Ice Formation on Kaolinite: Insights from Molecular Dynamics Simulations