Not long ago, chemical computation was considered a specialty area requiring extensive computer knowledge, power, and time. Over the past decade, however, it has changed from the arcane pursuit of a few advanced university researchers in the area of physical chemistry to a familiar tool used by a wide range of chemists. Nevertheless, it has required its practitioners to have extensive knowledge of computer programming and a thorough understanding of theoretical chemical concepts and as a result usually was reserved for the graduate curriculum. Now a further metamorphosis is in progress, as computational chemistry moves into the undergraduate curriculum, often using off-the-shelf software--commercial packages or adaptations of them that are readily shared by their creators. As we put this issue together, we realized that many of the articles involved sophisticated computations that would not have been possible a few years ago in the courses described. Further, the hard and software used was widely available at a reasonable cost. Some of the articles focus on the teaching of computational methods and others simply incorporate it as a facet in their overall strategy; however, taken together, they reflect a strong trend to utilize a diverse set of readily available methods and products in the undergraduate curriculum.

The most familiar recent use of computational chemistry is the computer design of molecules in organic, medicinal, and biochemistry. However, computational chemistry is useful for inorganic chemists as well and is now migrating to undergraduate courses. Lipkowitz, Pearl, Robertson, and Schultz (page 105) make a strong case for its inclusion and present a two-week component they have developed for their senior-level laboratory course. Comba and Zimmer (page 108) offer a review of inorganic molecular mechanics calculations, which is designed for the novice and includes the basic equations, their application to inorganic molecules, and a discussion of the how to evaluate the reliability of the results. A computational experiment has been specifically designed for the undergraduate laboratory by Bakalbassis, Stiakaki, Tsipis, and Tsipis (page 111). The students use an atom-superposition and electron-delocalization molecular orbital model to predict the structural, spectroscopic, and energetic properties of highly ionic metal-containing systems. The exercise introduces students to the value of computational experiments as an alternative to wet-lab work and teaches enough quantum theory to make them comfortable with current literature.

For teachers of organic chemistry, Delaware and Fountain (page 116) analyze how models can actually hinder learning in the introductory course if presented passively and describe how to use computer visualizations of reactions in an active, cooperative learning mode. They argue that these computational exercises need to be embedded in a carefully planned learning system to be effective. In similar fashion, Sauers (page 114) finds that a computer-assisted molecular modeling experiment is an effective way of making the concept of "steric interactions" more accessible. The theoretical number of isomers and derivatives of organic compounds is another concept difficult to visualize, and the calculations that would used for enumeration are complex enough that they are not usually brought into the undergraduate curriculum. However, Novak (page 120) demonstrates that widely available PC software, such as Mathematica, can be used by undergraduates along with the Polya enumeration method to enumerate derivatives and see the connection between these numbers and the symmetry of the parent molecule. A different use of computational software in biochemistry than the usual computer-assisted design of molecules is the main focus of a Computer Series article by Letkeman (page 165), who models the complex interactions of metal ions in human blood serum.

Featured on the Cover