User:Polyoxy/sandbox

SANDBOX version for the new page about Hirshfeld surface

A mathematical concept that describes the nature of the interaction of molecules (including charged molecules and complex polyatomic ions) with each other, in contrast to chemical bonds that describe the interaction within molecules. One of the modern approaches used to describe molecules in modern crystallography.

This approach is an attempt to go beyond the existing paradigm - internuclear distances and angles, packing diagrams of crystals with molecules represented using various models, and identification of close contacts that are considered important, and consider molecules as an "organic whole", thereby fundamentally replacing discussion of particular intermolecular interactions for impartial identification and quantification of the totality of all short contacts (while retaining the possibility of dividing these interactions according to their types). This approach may be of particular importance for biomolecules. An accessible description of the method is given in the textbook[1]

The Hirschfeld surface (HRS) arose as a result of an attempt to determine the space occupied by a molecule in a crystal in order to separate the electron density of a crystal into molecular fragments [2]. Hirschfeld surfaces were named after F. L. Hirschfeld. Hirschfeld's original paper on this division has attracted about 800 citations to date, more than 75% of them in the last five years. He proposed a scheme for separating the electron density in a crystal and a weight function for each atom in a molecule [3].

Currently, the program CrystalExplorer is used to calculate the Hirschfeld surface.

Some examples of the application of the Hirschfeld surface [1], [4], [5]. For relatively simple molecules, the Hirschfeld surface can be generated directly on the website of the journal Acta Crystallographica Sec.E - Crystallographic Communications, for example, for the morpholinium cation [2], when you press the 3D-view button, there is an option to generate the Hirschfeld surface and after selecting the desired fragment, the following image is obtained :