Superfluidity inH2Films

Path integral Monte Carlo calculations were used to study a 2D system of H{sub 2} molecules. The ground state on a flat substrate is a triangular lattice, a localized solid. We find that the introduction of some weakly attractive impurities (specifically alkali metal atoms) in the right concentration ({approximately}0.01 {Angstrom}{sup {minus} 2}) stabilizes a {ital liquid} hydrogen phase of concentration 0.04 {Angstrom}{sup {minus}2} which undergoes a Kosterlitz-Thouless superfluid transition below approximately 1.2 K. {copyright} {ital 1997} {ital The American Physical Society}