New quantum chemical methodology is of little use until it has been implemented into a software package that research workers can use. With this in mind, we have recently released Version 4 of the Q-Chem package, which is used by many groups around the world, and which is the computational engine inside the popular Spartan software package. As well as benefiting the scientific community, it also provides an excellent mechanism by which the work of students and postdocs can be made available, quickly and efficiently, to an international audience.
We have also developed an interface between the Q-Chem and CHARMM packages, allowing researchers to study very large chemical systems using a mixture of quantum mechanics and molecular mechanics. This has allowed us, for example, to investigate the mechanism of the chorismate mutase catalysed Claisen rearrangement.