General Atomic and Molecular Electronic Structure System

Chemical calculations that predict structures, energetics, and other properties of experimentally known or unknown molecules provide a fundamental resource for chemical research today. The basis of these calculations lies in an area of theoretical chemistry called molecular quantum mechanics. This science relates molecular properties to the motion and interaction of electrons and nuclei. Since the chemical properties of atoms and molecules are determined by their electronic structure, it is necessary to understand the nature of the motions and energies of the electrons and nuclei.

The understanding of molecular systems at this detailed level requires high level mathematical formulations that govern and allow prediction of molecular structure and properties. The ultimate goal of these calculations is the application to problems of general chemical/experimental interest such as a) the determination of reaction mechanisms, b) the study of the details of molecular forces and their role in structure determination, and c) the calculation of detailed potential energy surfaces and dynamics for reaction processes. Illucidations in these areas in turn lead to advancements in areas such as materials chemistry, electronics, environmental chemistry, and medicinal chemistry.

The degree of complexity in these types of molecular applications has caused a greater focus on advanced high performance computing methods, such as massive parallelization, more sophisticated visualization, and robust networked communications for data transfers. The importance of parallel computers in increasing the size and complexity of chemical systems that can be treated with quantum mechanical techniques has been realized for some time now by many groups. Here we report on results of GAMESS, General Atomic and Molecular Electronic Structure Systems, a quantum chemistry program which solves the Schrödinger Equation at various levels, leading to direct quantitative predictions of chemical phenomena from first principles (ab initio).