Kagome topology in two-dimensional noble-metal monolayers

Two-dimensional (2D) metallic kagome lattices provide an ideal platform for exploring geometric frustration and lattice stability in elemental systems. Motivated by recent realizations of goldene and kagome goldene, we investigate free-standing kagome monolayers of Cu, Ag, and Au using first-principles calculations and ab initio molecular dynamics. All systems satisfy the 2D Born stability criteria. Phonon calculations show that the unstrained kagome phase is dynamically unstable, while moderate biaxial tensile strain stabilizes Ag and Au. Finite-temperature simulations reveal rapid reconstruction in Cu, metastability in Ag, and competing kagome and trigonal motifs in Au. • Strain stabilizes Ag and Au kagome monolayers but fails for Cu. • Kagome topology yields low stiffness and strong lattice softening. • Gold shows competing kagome and trigonal phases at finite temperature.