AN EXPERIMENTAL CHEMISTS GUIDE TO ABINITIO QUANTUM-CHEMISTRY

This article is not intended to provide a cutting edge, state-of-the-art review of ab initio quantum chemistry. Nor does it offer a shopping list of estimates for the accuracies of its various approaches. Unfortunately, quantum chemistry is not mature or reliable enough to make such an evaluation generally possible. Rather, this article introduces the essential concepts of quantum chemistry and the computational features that differ among commonly used methods. It is intended as a guide for those who are not conversant with the jargon of ab initio quantum chemistry but who are interested in making use of these tools. In sections I-IV, readers are provided overviews of (i) the objectives and terminology of the field, (ii) the reasons underlying the often disappointing accuracy of present methods, (iii) and the meaning of orbitals, configurations, and electron correlation. The content of sections V and VI is intended to serve as reference material in which the computational tools of ab initio quantum chemistry are overviewed. In these sections, the Hartree-Fock (HF), configuration interaction (Cl), multiconfigurational self-consistent field (MCSCF), Moller-Plesset perturbation theory (MPPT), coupled-cluster (CC), and density functional methods such as X-alpha are introduced. The strengths and weaknesses of these methods as well as the computational steps involved in their implementation are briefly discussed.