Adsorption of a water molecule on the MgO(100) surface as described by cluster and slab models

Abstract

The interaction of a water molecule with the (100) surface of MgO as described by cluster models is studied using MP2, coupled MP2 (MP2C) and symmetry-adapted perturbation theory (SAPT) methods. In addition, diffusion Monte Carlo (DMC) results are presented for several slab models as well as for the smallest, 2X2 cluster model. For the 2X2 model it is found that the MP2C, DMC, and CCSD(T) methods give nearly the same potential energy curve for the water-cluster interaction, whereas the potential energy curve from the SAPT calculations differs slightly from those of the other methods. The interaction of the water molecule with the cluster models of the MgO(100) surface is weakened upon expanding the number of layers from one to two and also upon expanding the description of the layers from 2X2 to 4X4 to 6X6. The SAPT calculations reveal that both these expansions of the cluster model are accompanied by reductions in the magnitudes of the induction and dispersion constributions. The best estimate of the energy for binding an isolated water molecule to the surface obtained from the cluster model calculations is in good agreement with that obtained from the DMC calculations using a 2-layer slab model with periodic boundary conditions.

Comparing van der Waals DFT methods for water on NaCl(001) and MgO(001)

“…Karaltis et al reported a benchmark energy value of 0.48 eV for water monomer adsorption on MgO(001) based on diffusion Monte Carlo (DMC) calculations for a 2-layer slab. 41 Our vdW-DF-cx and optPBE-vdW values for the monomer/MgO(001) system agree quite well with their value. We note, however, that the two benchmark values for monomer adsorption that we refer to in our paper, namely, the CCSD(T) value for NaCl 14 and the DMC value for MgO, 41 are very similar in magnitude, which we find slightly disturbing, as the molecule on MgO should be expected to be more strongly bound.…”

Recent developments in symmetry‐adapted perturbation theory

“…204 The largest calculations of this kind involve a SAPT0 analysis of the interaction between benzene (or its fluorinated derivatives) and a graphene nanoflake as large as C 150 H 30. 205,206 In addition to adsorption on carbon nanostructures, interactions between small molecules and cluster models of other surfaces such as MgO, 207 TiO 2 , 208 or a metal organic framework 209 have also been subjected to the SAPT and/or SAPT(DFT) decompositions.…”

A comparison between quantum chemistry and quantum Monte Carlo techniques for the adsorption of water on the (001) LiH surface

“…This represents the leading error of a DMC calculation, but it benefits from a number of appealing properties which contrast with quantum chemical methods, such as a very minor dependence on basis set, as well as a low-scaling with respect to system size. DMC techniques are increasingly used to understand molecular adsorption at periodic surfaces 4,5,11,12 .…”