Bonding in Molecular Crystals from the Local Electronic Pressure Viewpoint

TL;DR

This paper introduces a novel approach to understanding chemical bonds in molecular crystals by analyzing the internal electronic pressure derived from electron density, providing a physically meaningful bonding descriptor.

Contribution

It develops a method to relate local electronic pressure to chemical bonding features in molecular crystals using density functional theory.

Findings

Internal pressure regions correlate with bond types

Method applied successfully to benzene, formamide, and chromium hexacarbonyl

Electronic pressure reveals specific bond features

Abstract

The spatial distribution of the internal pressure of an electron fluid, which spontaneously arises at the formation of a molecule or a crystal, is linked to the main features of chemical bonding in molecular crystals. The local pressure is approximately expressed in terms of the experimental electron density and its derivatives using the density functional formalism and is applied to identify the bonding features in benzene, formamide and chromium hexacarbonyl. We established how the spatial regions of compression and stretching of the electron fluid in these solids reflect the typical features of chemical bonds of different types. Thus, the internal electronic pressure can serve as a bonding descriptor, which has a clear physical meaning and reveals the specific features of variety of the chemical bonds expressing them in terms of the electron density.