The ONIOM method and its applications

The fields of theoretical and computational chemistry have come a long way since their inception in the mid-20th century. Fifty years ago, only rudimentary approximations for very simple molecules could be performed. Thanks in part to the ongoing development of very fast computers, and the efforts of theoretical chemists in developing fast and accurate quantum mechanical (QM) methods for calculating electronic energies of atoms and molecules, theoretical and computational chemistry can now give reliable geometries, energies, reactivities, and electronic properties for molecules. Such information has become indispensable in understanding and explaining experimental results that would be otherwise difficult to interpret.