Structural prediction of host-guest structure in lithium at high pressure

Prutthipong Tsuppayakorn-aek,Thiti Bovornratanaraks,Rajeev Ahuja,Teeraphat Watcharatharapong,Wei Luo

doi:10.1038/s41598-018-23473-5

Abstract

Ab initio random structure searching (AIRSS) technique is used to identify the high-pressure phases of lithium (Li). We proposed the transition mechanism from the fcc to host-guest (HG) structures at finite temperature and high pressure. This complex structural phase transformation has been calculated using ab initio lattice dynamics with finite displacement method which confirms the dynamical harmonic stabilization of the HG structure. The electron distribution between the host-host atoms has also been investigated by electron localization function (ELF). The strongly localized electron of p bond has led to the stability of the HG structure. This remarkable result put the HG structure to be a common high-pressure structure among alkali metals.

Highlights

Lithium (Li) is one of the most fascinating element in the periodic table and continues to attract a lot of attention due to the outstanding properties suitable for several applications, for example, battery technology[1], hydrogen storage[2], high electrical resistance[3], high superconducting transition temperature[4]
We refer the predicted stable structure that the I4/mcm is the periodic approximations to the incommensurate host-guest structure as the new structure of high-pressure Li of I4/mcm symmetry is composed of two structures
In order to accurately calculate the dependence of cH/cG of the HG on applied pressure, we present the stability of the HG structure through various commensurate analogues with respect to the cH/cG = 4/3

Summary

Introduction

Lithium (Li) is one of the most fascinating element in the periodic table and continues to attract a lot of attention due to the outstanding properties suitable for several applications, for example, battery technology[1], hydrogen storage[2], high electrical resistance[3], high superconducting transition temperature[4]. Li is one of central interest in many disciplines, especially in high pressure physics It is the huge interest in the theoretical study[5] and the experimental observation[6] as there is the stability of some of the complex structure. In a recent theoretical study by Pickard and Needs[18], the low-pressure close-packed structures were reported to be able to transform into the HG structure at terapascal pressures. They have shown that the formation of s-p hybridized bonds described by a two-component model consisting of positive ions and interstitial electron blobs at very high pressures. Our findings provide a significant advance in the understanding of the behavior of solid Li at high pressure

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Conclusion