Orientational phase transition of solid ortho -hydrogen

Abstract

Ground state of the quantum anisotropic planar rotor model: A finite size scaling study of the orientational order-disorder phase transition Broken symmetry phase transition in solid HD: a manifestation of quantum orientational melting Low Temp. Phys. 24, 518 (1998); 10.1063/1.593621Phase transitions in two-dimensional monolayer films on the (110) face-centered-cubic crystal surface Monte Carlo simulations of the γ-β, α-γ, and α-β phase transitions of nitrogen From the orientational dependence of the quadrupole energies, it is assumed that hydrogen molecules can take only four orientations characterized by the symmetry axis pointing to the ͓111͔ direction in the face-centered cubic lattice. It is shown that solid ortho-hydrogen undergoes the first-order phase transition for the molecular orientations. The transition temperature is derived in the mean-field approximation, and reexamined by means of the computer simulation. The intensity of x-ray diffuse scattering caused by orientational disorder shows an anomalous behavior at the transition temperature.