Force-Field and Molecular Orbital Calculations in Organosulfur Chemistry

Abstract

Chemical structure and energy calculations¹ are unique among the available research tools in that they do not require the molecule in question to have been made or isolated — or even that it is capable of existence. Calculations are capable of delivering structures, energies and electronic properties such as dipole moments, charge distributions or ionization potentials with reasonable accuracy at a fraction of the cost (both financial and in time and effort) of comparable experimental studies. Two main types of structure and energy calculation are available: force-field (molecular-mechanics) and molecular orbital (MO) calculations. The latter can be subdivided into the semiempirical (MINDO/3, MNDO, AM1, PM3 etc.) and ab initio techniques. The object of this article is to provide an overview of the cost (in computer time), applicability and accuracy of the various methods.