Answers
Chapter 1, Harder Questions, Answers
Q1
Was there computational chemistry before electronic computers were available?
Computational chemistryas the term is now understoodarose at about the same
time as electronic computers became available to chemists:
In 1951 an international conference was held at Shelter Island near Long Island in New
York, N.Y. Most of the leading figures in quantum chemistry were present. Two persons
there symbolized the phasing out of desktop mechanical calculators (Prof. Kotani from
Japan) and the phasing in of electronic digital computers (Prof. Roothaan of the United
Sates). That was the first major conference with a focus on the emerging computer in
theoretical chemistry [1].
With heroic effort, one of the very first molecular mechanics calculations, on a
reasonably big molecule (a dibromodicarboxybiphenyl), was done by the Westhei-
mer group, ca. 1946, presumably with at most a mechanical calculator [2]. Molec-
ular mechanics is genuine computational chemistry, but is far less numerically
intensive than quantum mechanical calculations. Nothing remotely like the quantity
and level of complexity of the calculations we see today would be possible without
electronic computers. One can make a case that computational chemistrywithout
the electronic computer was essentially stillborn, ca. 1950.
To be fair, H€uckel molecular orbital calculations, which can be executed with
pencil and paper, might legitimately be held to fall within the purview of computa-
tional chemistry, and these were first done in the 1930s [3] (attaining great popu-
larity in the 1950s and 1960s [4]). Computational chemistry thus blends into
traditional theoretical chemistry, a good part of which – much of chemical thermo-
dynamics – was almost singlehandedly created in the late 1800s, by Josiah Willard
Gibbs [5].
Histories of the development of computational chemistry in various countries
can be found in the continuing seriesReviews in Computational Chemistry[6].
E.G. Lewars,Computational Chemistry,
DOI 10.1007/978-90-481-3862-3,#Springer ScienceþBusiness Media B.V. 2011
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