At TIPS journal club meeting held on February 18, 2019, the topic of “Modeling Large Molecules Using the ONIOM Method Implemented in Gaussian Program” was presented by Dr. Jalalimanesh. A brief summary of this presentation is in below.
The ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) is a computational approach developed by Morokuma and co-workers. ONIOM is a hybrid or multiscale method that attempts to combine the accuracy of quantum mechanics with the speed of molecular mechanics. In an ONIOM method, a large molecule is divided into multiple fragments. Different theoretical methods, ranging from very expensive and accurate methods to less expensive and accurate methods, are then applied to the different fragments to produce reliable geometry and energy at reduced computational time. In the last two decades, ONIOM has been widely and successfully applied to study the structure and structure-related properties of biological systems (such as proteins and DNA/RNA). This method can serve as a powerful tool to model reaction mechanisms of pharmaceutically relevant targets, and for studying binding phenomena found within pharmaceutical drug discovery programs.