Publication Year



Chemistry, computational chemistry, calculations, computers, molecules


Chemistry | Computer Sciences | Physical Sciences and Mathematics


Recently the computer graphics systems and memory capabilities necessary to perform detailed chemical calculations have diminished enough in cost to become feasible for use by more than a few specialized laboratories. Before the last four or five years, computational chemistry was limited to methods in which the mathematics remained sufficiently simple and could be done relatively easily (for example, the unextended Huckel method, or molecular mechanics force field methods). Complicated chemical systems required more computer time and memory than were available, which limited calculations to molecules small enough that the computer would finish the procedure in a reasonable amount of time (weeks of computer calculations). With these limited capabilities, most of the work being done was performed by computer specialists, and the programs were not designed to be used by novices. This is no longer the case, and several different programs offering a range of types of calculations are now available. Computational chemistry is becoming a tool for analysis much like NMR, and the programs available are evolving at a rapid pace, both in what they can accomplish and in how they interact with the user.

The calculational methods employed by these programs can be grouped into three basic types: molecular mechanics, ab initio, and semi-empirical methods. Each of these procedures operates under very different calculatory models and requires different programming mechanisms. The three methods have their own sets of strengths and weaknesses, and each is most suitable for particular types of compounds.

Department 1 Awarding Honors Status