 
Summary: Computational Organic Chemistry: The "Can" and "Can't" be Done with Non
Supercomputers in Aromatic Chemistry.
Amnon Stanger
Schulich faculty of Chemistry and The LiseMeitnerMinerva Center for
Computational Quantum Chemistry, Technion Israel Institute of Technology, Haifa
32000, Israel Fax: (+) 97248293944. Email: stanger@tx.technion.ac.il
Abstract
Computational organic chemistry relies on solving the Schrödinger equation with the
necessary approximations for obtaining the properties (e.g., geometries, spectra, NMR
chemical shifts, transition states etc.) for gaining understanding of organic reactions
organic reactivity and other properties (e.g., different types of spectra). Currently the
methods include incomplete basis sets, HartreeFock approximation, several methods
of postHartreeFock calculations for describing electron correlation and different
DFT functional. The inherent problematic of these computations has to do with the
CPU time. Thus, for an accurate description of a system a large basis set has to be
employed. However, the CPU time for HartreeFock and DFT calculations is
proportional to N4
(N is the number of basis functions) and may go as high as N8
in
several postHartreeFock calculations. In addition, parallelization is not always
