Fast Semistochastic Heat-Bath Configuration Interaction

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This paper presents in detail our fast semistochastic heat-bath configuration interaction (SHCI) method for solving the many-body Schrodinger equation.

• We identify and eliminate computational bottlenecks in both the variational and perturbative steps of the SHCI algorithm.
• We also describe the parallelization and the key data structures in our implementation, such as the distributed hash table.
• The improved SHCI algorithm enables us to include in our variational wavefunction two orders of magnitude more determinants than has been reported previously with other selected configuration interaction methods.