Variational Monte Carlo configuration-interaction approach for multielectron atoms within the multiconfigurational Dirac-Hartree-Fock framework

In this work, we present a configuration-interaction method based on the variational Monte Carlo approach, implemented within the multiconfigurational Dirac-Hartree-Fock framework, to address the challenges of large basis sets in high-precision calculations for multielectron atoms. We validate its effectiveness on small basis set atomic systems, demonstrating strong convergence consistency. Extending the method to larger basis set atomic systems, we compute energy levels and transition parameters, showing that the variational Monte Carlo configuration-interaction method reduces the number of configurations by an average of 94% while maintaining comparable accuracy in energy level structure and transition parameters. This reduction in computational cost enables precise atomic structure calculations for systems with prohibitively large basis sets.