Recent work has identified over-structuring of molecular interactions due to too strong electrostatic interactions among charged molecules and ions. This artifact has been traced to the lack of electronic polarizability in classical molecular dynamics simulations. A way to effectively remedy this behavior in aqueous solutions is to reduce the atomic charges of the charged species by an inverse root of the electronic contribution to the permittivity, i.e. by a factor close to 75 % in the case of water. The so-called ECC-R (Electronic Continuum Correction with Rescaling) method applies the scaling of charges together with rescaling van der Waals parameters (which are typically optimized to provide good interatomic distances with full charges). The resulting models were found to yield good agreement not only with structural data, in fact improving the distribution of contact and solvent-separated ion pairs, but also with dynamic data. The ECC-R approach has already been successfully used for the study of atomic ions (Na +, Ca2+, Cl-) and its applications to multi-atomic ions are emerging. In our recent study, we have shown that the ECC-R approach was essential to obtain good agreement with reference AIMD data when modeling hydrogenoxalate and oxalate ions interacting with water. However, when moving from homogeneous solutions to interactions of ions and molecules with charged surfaces, the question how to model the interactions between the solids and aqueous species arises. In this contribution, we apply the ECC-R approach to modeling charged mineral surfaces, specifically (110) rutile (TiO2) and (101) quartz (SiO2), and their interactions with monoatomic ions (Na +, Rb+, Sr2+, Cl-). The assignment of the partial charges to surface atoms will be discussed and the results compared against the X-ray scattering experimental data [Kohli 2010, Bellucci 2015] and ab initio quantum calculations. The results (density profiles, interatomic interactions) will be also compared to our previously published results of the same systems obtained without the ECC-R method. This comparison will allow the benefits of the ECC-R method to be assessed for the study of similar systems.

Modelling of solid-liquid interactions using scaled charges in accord with the Electronic continuum correction

255th National Meeting (2018)

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