Space-time trade-off optimization for a class of electronic structure calculations

The accurate modeling of the electronic structure of atoms and molecules is very computationally intensive. Many models of electronic structure, such as the Coupled Cluster approach, involve collections of tensor contractions. There are usually a large number of alternative ways of implementing the tensor contractions, representing different trade-offs between the space required for temporary intermediates and the total number of arithmetic operations. In this paper, we present an algorithm that starts with an operation-minimal form of the computation and systematically explores the possible space-time trade-offs to identify the form with lowest cost that fits within a specified memory limit. Its utility is demonstrated by applying it to a computation representative of a component in the CCSD(T) formulation in the NWChem quantum chemistry suite from Pacific Northwest National Laboratory.