Portably parallel construction of a configuration‐interaction wave function from a matrix–product state using the Charm++ framework

The construction of configuration‐interaction (CI) expansions from a matrix product state (MPS) involves numerous matrix operations and the skillful sampling of important configurations in a large Hilbert space. In this work, we present an efficient procedure for constructing CI expansions from MPS employing the parallel object‐oriented Charm++ programming framework, upon which automatic load‐balancing and object migrating facilities can be employed. This procedure was employed in the MPS‐to‐CI utility (Moritz et al., J. Chem. Phys. 2007, 126, 224109), the sampling‐reconstructed complete active‐space algorithm (SR‐CAS, Boguslawski et al., J. Chem. Phys. 2011, 134, 224101), and the entanglement‐driven genetic algorithm (EDGA, Luo et al., J. Chem. Theory Comput. 2017, 13, 4699). It enhances productivity and allows the sampling programs to evolve to their population‐expansion versions, for example, EDGA with population expansion (PE‐EDGA). Further, examples of 1,2‐dioxetanone and firefly dioxetanone anion (FDO−) molecules demonstrated the following: (a) parallel efficiencies can be persistently improved by simply by increasing the proportions of the asynchronous executions and (b) a sampled CAS‐type CI wave function of a bi‐radical‐state FDO− molecule utilizing the full valence (30e,26o) active space can be constructed within a few hours with using thousands of cores.