Concurrent processing of VQE-UCCSD calculations with the FMO scheme

The fragmentation-based method has attracted interest to reduce the computational cost for quantum computation of quantum chemistry. Previously (K. Sugisaki et al., J. Comput. Chem. 2024, 45, 2204), we reported the simulation results of the variational quantum eigensolver (VQE) of unitary coupled cluster singles and doubles (UCCSD) under the fragment molecular orbital (FMO) framework, where the influence of Trotter error was highlighted for (FH)3 and H2O-(FH)2 models. In this report, the concurrent processing for the fragment list is adapted with examples of Li(I)-(H2)n (n=4,6) clusters. VQE-UCCSD energies and timing data are presented to illuminate the issues of practical applications.