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# Bader's Theory of Atoms in Molecules (AIM) and its Applications to Chemical Bonding

## Details

**Authors** Kumar, P. Shyam Vinod and Raghavendra, V. and Subramanian, V.

**Year** 2016

**Publisher** Journal of Chemical Sciences

**Kind of work** article

**Discipline** Chemistry

**Secondary disciplines** Physics

**Applied** false

[Read it at the publisher](https://doi.org/10.1007/s12039-016-1172-3) 
10.1007/s12039-016-1172-3

## In authors' words

### What they set out to do (purpose)

To present the basic theory and applications of the Quantum Theory of Atoms in Molecules, with examples from weak and hydrogen-bonded molecular systems.

### Who or what was studied (sample)

Molecular systems including water, ethane, cyclopropane, cubane, benzene dimers, and H3O+ water clusters.

### What they found (results)

An atom is defined as an attractor of the electron density gradient together with its basin, bounded by a surface of zero flux in the density gradient. A bond critical point and bond path between two nuclei are taken as the signature of bonding. Covalent bonds show high density and a negative Laplacian at the critical point, while weak interactions show low density and a positive Laplacian. The T-shaped benzene dimer is marginally more stable (-1.60 kcal/mol) than the parallel-displaced one (-1.20 kcal/mol). In H3O+ clusters, density at the hydrogen-bond critical point falls from about 0.16 a.u. to about 0.03 a.u. across solvation shells, and stabilization per hydrogen bond falls from about 49 to about 19 kcal/mol.

## Commentary

### In short

A perspective article reviewing a quantum-mechanical way of defining atoms inside molecules by the topology of electron density, and applying it to covalent, weak and hydrogen bonds.

### Response

The theory draws a boundary around each atom (a zero-flux surface), treats the molecule as composed of those bounded atomic basins (a part-whole decomposition), and reads bonding from the link between two nuclei (bond path and critical point). The distinction, system and relationship patterns each carry weight, since the account would be incomplete without the boundary, the atoms-as-parts and the bond-as-connection. Caveats: this is a review of an existing theory, not a new study; no perspective pattern is claimed; the review's wording on additivity and open systems was not confirmed from the page; and the original 1985 Bader paper would be the stronger primary source.

**Patterns it shows** D, S, R

Shows the structure is there

**Added** 2026-10-18

**How to cite this** Kumar, P. Shyam Vinod and Raghavendra, V. and Subramanian, V. (2016). Bader's Theory of Atoms in Molecules (AIM) and its Applications to Chemical Bonding. Journal of Chemical Sciences.