Amorphous Silica Slab Models with Variable Surface Roughness and Silanol Density for Use in Simulations of Dynamics and Catalysis
Pubudu N. Wimalasiri, Nuong P. Nguyen, Hasini S. Senanayake, Brian B. Laird, Ward H. Thompson
Abstract
Silica is both ubiquitous in nature and important in a wide range of applications ranging from drug delivery to catalysis. This has spawned significant interest in modeling silica, particularly the amorphous solid, and its interactions with liquids, adsorbates, and embedded active sites. One of the challenges is developing descriptions that accurately represent the synthesized materials used in experiments when key properties, such as the surface roughness and distribution of silanol groups, cannot be readily measured. Here, we implement a simple, tunable melt-cleave-quench-functionalize approach to create amorphous silica slabs with variable characteristics. We use it to generate 2000 atomistically distinct slab models, based on the widely used the van Beest, Kramer, van Santen (BKS) potential, that differ in their atomistic roughness, defect site density, ring distribution, silanol density, and spatial arrangement of silanols. The surfaces are demonstrated to be consistent with available experimental data and stable within the ReaxFF bond order-based reactive force field. These amorphous silica slab models should thus be of use in a variety of computational studies of interfacial properties.