A massively multicore parallelization of the Kohn-Sham energy gradients

In a previous article [Brown et al., J Chem Theory Comput 2009, 4, 1620], we described a quadrature-based formulation of the Kohn-Sham Coulomb problem that allows for efficient parallelization over thousands of small processor cores. Here, we present the analytic gradients of this modified Kohn-Sham scheme, and describe the parallel implementation of the gradients on a numerical accelerator architecture. We demonstrate an order-of-magnitude acceleration for the combined energy and gradient calculation over a conventional single-core implementation.