An auto-initializing algorithm to determine electronic ground states from random Slater determinants

Accurate quantum many-body calculations often depend on reliable reference states or good human-designed ansätze, yet such knowledge can become unreliable in hard problems like strongly correlated systems. Here we show that high-accuracy many-body ground states can be discovered directly from random Slater determinants. We introduce the Trimmed Configuration Interaction (TrimCI) method, which self-refines by iteratively expanding and trimming configurations in the variational space. TrimCI matches state-of-the-art accuracy using orders of magnitude fewer determinants and computer time: 10⁶-fold fewer than a recent quantum computing calculation on an iron-sulfur cluster, 10⁵-fold fewer than a leading classical method on a larger iron-sulfur cluster in nitrogenase, and over 99% of the ground-state energy of a strongly correlated lattice system from 10^-28 of its Hilbert space, exceeding quantum Monte Carlo accuracy by orders of magnitude in some regimes. TrimCI thus provides an auto-initializing, accurate and highly efficient framework for quantum many-body systems, whose compact explicit wavefunctions enable direct and rapid evaluation of observables.