Stabilization and electronic topological transition of hydrogen-rich metal Li5MoH11 under high pressures from first-principles predictions

Prutthipong Tsuppayakorn-Aek,Thiti Bovornratanaraks,Wei Luo,Wiwittawin Sukmas,Rajeev Ahuja

doi:10.1038/s41598-021-83468-7

Abstract

Regarded as doped binary hydrides, ternary hydrides have recently become the subject of investigation since they are deemed to be metallic under pressure and possibly potentially high-temperature superconductors. Herein, the candidate structure of Li5MoH11 is predicted by exploiting the evolutionary searching. Its high-pressure phase adopts a hexagonal structure with P63/mcm space group. We used first-principles calculations including the zero-point energy to investigate the structures up to 200 GPa and found that the P63cm structure transforms into the P63/mcm structure at 48 GPa. Phonon calculations confirm that the P63/mcm structure is dynamically stable. Its stability is mainly attributed to the isostructural second-order phase transition. Our calculations reveal the electronic topological transition displaying an isostructural second-order phase transition at 160 GPa as well as the topology of its Fermi surfaces. We used the projected crystal orbital Hamilton population (pCOHP) to examine the nature of the chemical bonding and demonstrated that the results obtained from the pCOHP calculation are associated with the electronic band structure and electronic localized function.

Highlights

The success of experimental syntheses of metal hydrides has attracted considerable attention especially amongst the high-pressure research community, a corollary to discoveries—both experimental and theoretical—of a variety of interesting physical properties of these m aterials[1,2,3,4,5,6,7,8]
We further investigated the nature of the chemical bonding near the Fermi level by with the aid of the projected crystal orbital Hamilton populations calculation, which enables the determination of anti-bonding and bonding characteristics, e.g., covalent bonds, along energy r ange[51,52,53]
Our calculations show that by incorporating the zero-point energy evaluation the P63/mcm structure is thermodynamically and dynamically favored over the P63cm and R3c structures above 50 GPa The perspective of theoretical inspection points out that the P63mcm structure exists under high pressure adopting the hexagonal basis

Summary

Introduction

The success of experimental syntheses of metal hydrides has attracted considerable attention especially amongst the high-pressure research community, a corollary to discoveries—both experimental and theoretical—of a variety of interesting physical properties of these m aterials[1,2,3,4,5,6,7,8]. The superhydride Ce-H system, for instance, was successfully synthesized using the laser-heated diamond anvil cell (DAC) accompanied with synchrotron X-ray diffraction, which was theoretically confirmed by the evolutionary variable-composition simulation indicating that CeH9 adopts a hexagonal clathrate structure with the P 63/mmc symmetry and potentially produces hightemperature superconductivity with estimated Tc of 105–117 K at 200 GPa9 Another metal-hydride superconductor of LaH10 with Tc = 260 K, approaching room temperature, was synthesized and experimentally observed under pressure between 180–200 GPa10, while it was suggested by a subsequent theoretical study to adopt a sodalite-like clathrate structure with Fm3m symmetry and exhibit a decreasing trend in Tc under an increase of pressure[11]. We support results of electronic band structure and electron localized function by demonstrating the projected crystal orbital Hamilton population (pCOHP) method

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Conclusion