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Numerical routines for Fock states indexing and to handle creation andannihilation operators in the spanned multiconfigurational space are developed.From the combinatorial problem of fitting particles in a truncated basis ofindividual particle states, which defines the spanned multiconfigurationalspace, a hashing function is provided based on a metric to sort all possibleconfigurations, which refers to sets of occupation numbers required in thedefinition of Fock states. Despite the hashing function unambiguously relatesthe configuration to the coefficient index of the many-particle state expansionin the Fock basis, averages of creation and annihilation operators can be ahighly demanding computation, especially when they are embedded in atime-dependent problem. Therefore, improvements in the conversion betweenconfigurations after the action of creation and annihilation operators arethoroughly inspected, highlighting the advantages and additional memoryconsumption. We also exploit massive parallel processors from graphicsprocessor units with CUDA to improve a routine to act with the many-bodyHamiltonian matrix on the spanned multiconfigurational space, whichdemonstrated quantitatively the scalability of the problem. The improvementsshown here seem promising especially for calculations involving a large numberof particles, in which case, the optimized CUDA code provided a drasticperformance gain of roughly fifty times faster than a single core processor.The codes were consistently tested with an application to the Lieb-Liniger gas,evaluating the ground state and comparing with the analytical solution.

Hashing algorithms, optimized mappings and massive parallelization of multiconfigurational methods for bosons