Bonding in molecular crystals from the local electronic pressure viewpoint^*

* This paper is dedicated to Professor Andreas Savin on the occasion of his 65th birthday.

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 the variety of the chemical bonds expressing them in terms of the electron density.

GRAPHICAL ABSTRACT

KEYWORDS:

• Chemical bond
• internal electronic pressure
• electron concentration
• density functional theory

Acknowledgments

We thank Dr D. Yufit, Prof. S. Parsons and Dr L. Farrugia for sending us the experimental data for benzene, formamide and chromium hexacarbonyl.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

* This paper is dedicated to Professor Andreas Savin on the occasion of his 65th birthday.

Additional information

Funding

Russian Foundation for Basic Research [grant number 16-03-00057a (VGT and AIS)]; Spanish Ministerio de Economía y Competitividad (MINECO) [grant number FIS2013-46159-C3-1-P] ‘Grupos Consolidados UPV/EHU del Gobierno Vasco’ [grant number IT578-13 (I.V.T)].