Eric: A Special-Purpose Processor for ERI Calculations in Quantum Chemistry Applications

Ab initio molecular orbital (MO) calculation is useful for solving many challenging problems regarding the development of new drugs, chemicals, polymers, materials, and so on. In the EHPC (Embedded High Performance Computing) project, we are now developing a special-purpose computer system for ab initio MO calculations in order to reduce the calculation time. The sequential execution time of ab initio MO is O( $ N^4 $) where $ N $ is the number of basis functions, the heaviest computation being the electron repulsion integrals (ERI's). In order to accelerate ab initio MO calculations, it is necessary to develop a special-purpose processor for ERI calculation. Using the characteristics of ERI in the Obara algorithm makes it possible to reduce the calculation time. In this work, we investigate a chip-multiprocessor (CMP) architecture, called Eric, for an application-specific processor able to perform fast ERI computations.