Consistent van der Waals Radii for the Whole Main Group

TLDR

Atomic radii are imprecisely defined yet widely used, and Bondi’s van der Waals radii—derived from crystal and gas data—are the most common, though they cover only 28 of the 44 main‑group elements. The study aims to provide van der Waals radii for the remaining 16 main‑group elements that are compatible with Bondi’s scale. The authors derived the radii by fitting two‑parameter correlations between Bondi’s values and repulsive‑wall distances obtained from relativistic coupled‑cluster electronic structure calculations. The resulting radii (Å) are: Be 1.53, B 1.92, Al 1.84, Ca 2.31, Ge 2.11, Rb 3.03, Sr 2.49, Sb 2.06, Cs 3.43, Ba 2.68, Bi 2.07, Po 1.97, At 2.02, Rn 2.20, Fr 3.48, Ra 2.83.

Abstract

Atomic radii are not precisely defined but are nevertheless widely used parameters in modeling and understanding molecular structure and interactions. The van der Waals radii determined by Bondi from molecular crystals and data for gases are the most widely used values, but Bondi recommended radius values for only 28 of the 44 main-group elements in the periodic table. In the present Article, we present atomic radii for the other 16; these new radii were determined in a way designed to be compatible with Bondi's scale. The method chosen is a set of two-parameter correlations of Bondi's radii with repulsive-wall distances calculated by relativistic coupled-cluster electronic structure calculations. The newly determined radii (in Å) are Be, 1.53; B, 1.92; Al, 1.84; Ca, 2.31; Ge, 2.11; Rb, 3.03; Sr, 2.49; Sb, 2.06; Cs, 3.43; Ba, 2.68; Bi, 2.07; Po, 1.97; At, 2.02; Rn, 2.20; Fr, 3.48; and Ra, 2.83.