Page 12 - Strategies and Applications in Quantum Chemistry From Molecular Astrophysics to Molecular Engineer

Prefaces

Why this Book ?

Starting from pure academic knowledge, Quantum Chemistry has gained the rank of full
partner in most chemical research carried out today, from organic chemistry to solid state
chemistry, from biology to material sciences, from astrophysics to chemical engineering.
Evolution has been rapid.

After a promising start in the mid twenties, Quantum Chemistry then faced the first
technological block: the numerical barrier.
The consequence has been a flourishing of concepts still found in the present literature and
in the common langage of all physico-chemists when it comes to understanding the basic
phenomena.
Then appeared the time of computers. Quantum chemists developed semi-empirical codes
that rapidly evolved into ab-initio complex systems of programs. According to their
optimistic or pessimistic views, colleagues have seen this period either as that of semi
-quantitative or of semi-qualitative theoretical chemistry. Very recently came the age of
super computers, and a generation of quantum chemists have seen their dream come true: at
last, the quality of the calculation is in harmony with the quality of the concepts.

At a time when an increasing number of chemists are being dangerously attracted by the
fascination of supposedly easy computing, it seemed an appropriate opportunity to dedicate
a volume to Gaston Berthier. Born in 1923, a year in which the scientific community
celebrated the 10th anniversary of Bohr's quantum theory of the atom, but also the year
when de Broglie published the fundamental idea that the orbit of an electron is linked to a
stationary condition on the associated wave, Gaston Berthier took part in all the evolution
and unavoidable conflicts between the anciens and the modernes at each stage of
development of the discipline. Often in advance of his time, but never rejecting the past,
Gaston Berthier has inspired generations of young, and less young, scientists in almost
every branch of theoretical chemistry and its applications to experiment.

The title "Strategies and Applications in Quantum Chemistry" was chosen to illustrate his
dual philosophy. The response of former collaborators of Berthier, often former students,
always friends, has been overwhelming, as is evident from the size of this book.

Most of the signatures come from the community of the Theoretical Chemists of Latin
Expression, a melting pot conceived by Berthier and a few others. The contributions range
from the prefaces with a personal assessment by the first witnesses of Berthier's beginning
through a series of articles covering basic developments in MCSCF theory, perturbation
theory, basis sets, charge densities, wave function instabilities, correlation effects,
momentum space theory, through contributions to understanding EPR spectroscopy,
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