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A phase boundary for H-Pd(100) was calculated using the Metropolis (1953) algorithm and the embedded atom method (EAM) described by Daw and Foiles (1987). The calculated phase boundary agreed with an experimentally determined phase boundary in its curvature and the coverage at which maximum Tc appeared, but was about 125 K lower than the experimental phase boundary.
PdH is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pd is bonded to six equivalent H atoms to form a mixture of corner and edge-sharing PdH6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Pd–H bond lengths are 2.07 Å. H is bonded to six equivalent Pd atoms to form a mixture of corner and edge-sharing HPd6 octahedra. The corner-sharing octahedral tilt angles are 0°.
(Pd)6H2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional and consists of two hydrogen molecules and one Pd framework. In the Pd framework, Pd is bonded in a 8-coordinate geometry to eight equivalent Pd atoms. There are a spread of Pd–Pd bond distances ranging from 2.64–2.90 Å.
PdH is Wurtzite structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Pd is bonded to four equivalent H atoms to form corner-sharing PdH4 tetrahedra. There is one shorter (1.82 Å) and three longer (1.85 Å) Pd–H bond length. H is bonded to four equivalent Pd atoms to form corner-sharing HPd4 tetrahedra.
Pd4H3 is MAX Phase-derived structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three Pd4H3 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 3-coordinate geometry to three equivalent H atoms. All Pd–H bond lengths are 1.92 Å. In the second Pd site, Pd is bonded to six H atoms to form a mixture of edge and corner-sharing PdH6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.06 Å) and three longer (2.22 Å) Pd–H bond lengths. There are two inequivalent H sites. In the first H site, H is bonded to six Pd atoms to form a mixture of edge and corner-sharing HPd6 octahedra. The corner-sharing octahedral tilt angles are 6°. In the second H site, H is bonded to six equivalent Pd atoms to form a mixture of edge and corner-sharing HPd6 octahedra. The corner-sharing octahedral tilt angles are 6°.
(Pd)6H2 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional and consists of two hydrogen molecules and one Pd framework. In the Pd framework, there are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 8-coordinate geometry to eight Pd atoms. There are four shorter (2.64 Å) and four longer (2.78 Å) Pd–Pd bond lengths. In the second Pd site, Pd is bonded in a body-centered cubic geometry to eight equivalent Pd atoms.