# The covalent radii derived from the first-principle data

## TL;DR

This paper introduces a set of covalent radii derived from quantum-chemical calculations without empirical input, providing a first-principles basis that aligns well with existing empirical data and accounts for electron delocalization effects.

## Contribution

The authors present the first-principles covalent radii for several elements, derived from a large quantum-chemical dataset, including corrections based on electronegativity differences.

## Key findings

- First-principles radii agree with empirical data
- Deviations analyzed with electron delocalization considerations
- Electronegativity-based corrections improve radius estimates

## Abstract

We present a collection of covalent radii for the elements H, B, C, N, O, F, Si, P, S, Cl, Ge, As, Se, Br, derived from the recently introduced systematic non-empirical dataset of the covalent bond lengths. As the underlying bond lengths dataset was built basing on 26050 molecular geometries and bond graphs data obtained from quantum-chemical calculations with almost no input of empirical data, the presented covalent radii can be referred to as the first-principle ones. The obtained first-principle covalent radii are in good agreement with their empirical counterparts available in the literature. The distributions of deviations between the sum of proposed radii and the true bond lengths are analyzed in details, with emphasis put on the role of the electron delocalization on the bond lengths. Corrections to the additive covalent radii model due to the difference in the elements electronegativities are derived for both Pauling and Mulliken electronegativity scales.

---
Source: https://tomesphere.com/paper/1906.11724