We present a systematically-improvable approach to core excitations in
variational Monte Carlo. Building on recent work in excited-state-specific
Monte Carlo, we show how a straightforward protocol, starting from a quantum
chemistry guess, is able to capture core state's strong orbital relaxations,
maintain accuracy in the near-nuclear region during these relaxations, and
explicitly balance accuracy between ground and core excited states. In water,
ammonia, and methane, which serve as prototypical representatives for oxygen,
nitrogen, and carbon core states, respectively, this approach delivers
accuracies on par with the best available theoretical methods even when using
relatively small wave function expansions.Comment: 10 pages, 4 figures, 1 tabl