Metallic and superconducting gallane under high pressure

Abstract

Using our newly developed particle swarm optimization algorithm on crystal structural prediction, we characterized the pressure-induced structural transition sequence of gallane (GaH 3 ). As has been observed in alane (AlH 3 ), enthalpy calculations reveal that the Pm3n structure of GaH 3 becomes stable above 160 GPa, below which it is unstable with respect to elemental decomposition. Interestingly, the Pm3n structure is metallic, and the application of the Allen-Dynes modified McMillan equation reveals a high superconducting transition temperature (T c ), which reaches 86 K at 160 GPa and increases with decreasing pressure (T c = 102 K at 120 GPa). Our band structure calculations demonstrate that GaH 3 within the Pm3n structure is a highly ionic solid, where the ionicity of H atoms plays an important role in the predicted high temperature superconductivity.

Quantum-defect theory for−1/r4-type interactions

“…The energy bin concept [14,61,62] is useful not only in single-channel but also in multichannel formulations [39,53], where it can be used, for instance, to estimate the number of Fano-Feshbach resonances. A detailed example will be given in a separate publication on MQDT for ion-atom interactions.…”

“…III B 1. In a multichannel formulation [39,53], the same functions, and a short-range K c matrix, characterize not only the bound spectrum, but also the Fano-Feshbach resonances. A complete understanding of the negative energy states [29] will, however, generally require all three QDT functions, namely D c l and Θ c l , in addition to Φ c l .…”

“…(97), will be useful in cases where the energy dependence of K c is not negligible. These include some cases of electron-atom interactions, and maybe more importantly, some cases corresponding to effective single-channel descriptions of Fano-Feshbach resonances, for which the effective K c parameter can have substantial energy dependence around a narrow resonance [53]. charge-neutral systems in a range of energies around the threshold.…”

Pressure induced phase transitions in TiH2

“…High-pressure phases of many hydrides have been the subject of study for several years, [1][2][3][4][5][6][7][8][9][10][11] which has been fundamental to identify new equilibrium and metastable structures, those could even be quenchable. Interestingly, metallic phases of some compressed hydrides have been predicted to be high temperature superconductors, [2][3][4][5][6][7][8] and many others are promising compounds for hydrogen storage.…”

Perspective: Role of structure prediction in materials discovery and design

“…57 However, our structure searches suggest this phase to be unstable to decomposition at high pressures. High-temperature superconductivity was also predicted in a number of metallic hydrides [57][58][59][60][61][62][63][64][65][66][67] but most of the predicted T c 's were not realized. FIG.…”