Quantum chemistry in the 21st century (Special topic
article)
Christopher J. Barden and Henry F. Schaefer III
Center for Computational Quantum Chemistry, University
of Georgia, Athens, Georgia 30602 USA
Abstract: Quantum chemistry is the field in which solutions
to the Schrödinger equation are used to predict the properties
of molecules and solve chemical problems. This paper considers possible
future research directions in light of the discipline's past successes.
After decades of incremental developmentaccompanied by a healthy
dose of skepticism from the experimental communitythe ready availability
of fast computers has ushered in a "golden age" of quantum
chemistry. In this new era of acceptance, theoretical predictions often
precede experiment in small molecule chemistry, and quantum chemical
methods play an ever greater role in biochemical and other larger systems.
Quantum chemists increasingly divide their efforts along three fronts:
high-level (spectroscopic) accuracy for small molecules, characterized
by such techniques as Brueckner methods, r12 formalisms,
and multireference calculations; parameterization- or extrapolation-based
intermediate-level schemes (such as Gaussian-N theory) for medium molecules;
and lower-level (chemical) accuracy for large molecules, characterized
by density functional theory and linear scaling techniques. These tools,
and quantum chemistry as a whole, are examined here from a historical
perspective and with a view toward their future applications.