The best way to understand chemical bonding may be to take a view
appropriate to each individual system, a view which may be quite
different for various systems. Sometimes two very different views are
appropriate for the same system, and then the combination may even give
the parameters needed to estimate the bonding energy by hand. Density
Functional Theory, on the other hand, generally tries to take one view
as applicable to all systems, and proceeds computationally.In contrast
to the author's two previous well-known textbooks, Electronic Structure
and the Properties of Solids (1989) and Elementary Electronic Structure
(1999), in this book he tries to distill the essence of the
representation of electronic structure in a much briefer description. It
is shortened by focusing primarily on the bonding energies, the energy
gained in assembling atoms as a molecule or a solid, or as a solid with
a surface. A central point is that the same description of the
electronic structure which gives this cohesion, can also be used to
understand all of the other properties, though those other properties
are not emphasized here. The effort is characterized by the title, which
combines the modern word "theory" with the ancient effort of "alchemy"
to make sense of the material world.