Chapter 5
Exploring Chemistry Through the Source
Function for the Electron and the Electron
Spin Densities
Carlo Gatti, Ahmed M. Orlando, Emanuele Monza
and Leonardo Lo Presti
Abstract The Source Function, a chemical descriptor introduced by Bader and
Gatti in 1998, represents a challenging tool to see the electron density from an
unusual perspective. Namely, as caused, at any point in the space, by source
contributions operating at all other points of space. Summing up the local sources
over the atomic basins of a system, enable us to regard the electron density at any
system’s location as determined by smaller or larger contributions from all the
atoms or group of atoms of the system. Such decomposition of sources provides
valuable chemical insight and it may be applied, on the same grounds, to theoretically or experimentally derived electron densities. Two recent Source Function
developments, specifically its application to detect subtle electron delocalization
effects and its extension to the electron spin density sources are reviewed through
this chapter. An original application, as viewed through the eyes of the Source
Function, then follows each illustrated development. Precisely: (a) the electron
delocalization mechanisms in complex and non planar aromatic systems, like the
homotropylium cation and the 1,6-methano[10]annulene, and (b) the spin density
transferability properties in a series of n-alkyl radicals.
Keywords Source function Á Electron density Á Electron spin density Á Chemical
bonding Á Electron conjugation Á Aromaticity Á Non-planar aromatic frameworks Á
Chemical transferability Á Spin density transferability
C. Gatti (&) Á L. Lo Presti
CNR-ISTM, Via Golgi 19, 20133 Milan, Italy
e-mail: c.gatti@cnr.istm.it
L. Lo Presti
e-mail: leonardo.lopresti@unimi.it
C. Gatti Á A.M. Orlando Á L. Lo Presti
Center for Material Crystallography, Aarhus University, Langelandsgade 140,
8000 Aarhus, Denmark
A.M. Orlando Á E. Monza Á L. Lo Presti
Chemistry Department, Università degli Studi di Milano, Via Golgi 19,
20133 Milan, Italy
© Springer International Publishing Switzerland 2016
R. Chauvin et al. (eds.), Applications of Topological Methods
in Molecular Chemistry, Challenges and Advances in Computational
Chemistry and Physics 22, DOI 10.1007/978-3-319-29022-5_5
101
Exploring Chemistry Through the Source
Function for the Electron and the Electron
Spin Densities
Carlo Gatti, Ahmed M. Orlando, Emanuele Monza
and Leonardo Lo Presti
Abstract The Source Function, a chemical descriptor introduced by Bader and
Gatti in 1998, represents a challenging tool to see the electron density from an
unusual perspective. Namely, as caused, at any point in the space, by source
contributions operating at all other points of space. Summing up the local sources
over the atomic basins of a system, enable us to regard the electron density at any
system’s location as determined by smaller or larger contributions from all the
atoms or group of atoms of the system. Such decomposition of sources provides
valuable chemical insight and it may be applied, on the same grounds, to theoretically or experimentally derived electron densities. Two recent Source Function
developments, specifically its application to detect subtle electron delocalization
effects and its extension to the electron spin density sources are reviewed through
this chapter. An original application, as viewed through the eyes of the Source
Function, then follows each illustrated development. Precisely: (a) the electron
delocalization mechanisms in complex and non planar aromatic systems, like the
homotropylium cation and the 1,6-methano[10]annulene, and (b) the spin density
transferability properties in a series of n-alkyl radicals.
Keywords Source function Á Electron density Á Electron spin density Á Chemical
bonding Á Electron conjugation Á Aromaticity Á Non-planar aromatic frameworks Á
Chemical transferability Á Spin density transferability
C. Gatti (&) Á L. Lo Presti
CNR-ISTM, Via Golgi 19, 20133 Milan, Italy
e-mail: c.gatti@cnr.istm.it
L. Lo Presti
e-mail: leonardo.lopresti@unimi.it
C. Gatti Á A.M. Orlando Á L. Lo Presti
Center for Material Crystallography, Aarhus University, Langelandsgade 140,
8000 Aarhus, Denmark
A.M. Orlando Á E. Monza Á L. Lo Presti
Chemistry Department, Università degli Studi di Milano, Via Golgi 19,
20133 Milan, Italy
© Springer International Publishing Switzerland 2016
R. Chauvin et al. (eds.), Applications of Topological Methods
in Molecular Chemistry, Challenges and Advances in Computational
Chemistry and Physics 22, DOI 10.1007/978-3-319-29022-5_5
101