Revisiting Chemical System Size Using STREUSEL (Surface Topology Recovery Using Sampling of the Electric Field): The Role of Size in Atomic, Molecular, and Solid-State Properties

Abstract

Atomic, molecular, and porous material void space shape and size play a critical role in chemistry. The most familiar method was formalized by Bondi: the van der Waal radii and volume of atoms and molecules. However, the rigid sphere approximation of atoms fails to describe highly polarized chemical systems. To overcome this challenge, numerous other approaches based on electron density have been presented, but these approaches intrinsically struggle to describe the surface area and volume of cations. Herein, we revisit the timeless problem of assessing sizes of atoms, molecules and porous material void spaces, through examination of the electric field produced by these chemical systems. In this way, we are able to recover chemical volumes and surface areas from simple DFT calculations. We perform a series of benchmarks to ensure the generality of our approach and demonstrate that electric field calculations provide unique insights into quantifying sizes of ions and polar molecules. Our method further lays the foundation for the development of analytical interaction energies based on assessment of the Coulomb potential produced by molecules systems, while providing a rigorous approach to study size dynamics as a function of chemical environment. Beyond these advancements, we demonstrate the advantageous role of electric field-derived size in determining the void space characteristics of nanoporous, crystalline materials.