  A van Hove singularity (VHS) often significantly amplifies the electronic
instability of a crystalline solid, including correlation-induced phenomena
such as Hund's metallicity. We perform a systematic study on the interplay
between Hund's coupling and electronic structures with a VHS focusing on Hund's
metallicity. We construct a simplified tight-binding model targeting cubic
perovskite materials and test the effects of the VHS utilizing dynamical
mean-field theory with an exact diagonalization solver. The quasiparticle
weight and the low-frequency power exponent of the self-energy provide a
quantitative estimation of metallicity over the phase diagram. We find the VHS
to substantially enhance Hund's metallicity. The results here suggest a range
of parameters through which a VHS can bring great synergy with Hund's coupling.
