Electronic structure and electron-phonon coupling in LiBeH3

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Abstract
Using the augmented plane wave method the authors have studied the electronic structure of LiBeH3 assuming a cubic perovskite structure. This hydride is found to be a semiconductor with a very small indirect energy gap of 0.21 eV. By reducing the lattice constant from a=2.545 AA to a=2.459 AA to simulate a pressure effect, they obtain a metallic behaviour with a small value of the DOS at EF. In the metallic state, they have evaluated the electronic contribution eta of the electron-phonon coupling constant by means of the Gaspari and Gyorffy formalism (1972). At the H sites eta H is found to be larger than in superconducting PdH due to the presence of a sizable fraction of Hs states at EF. Provided that the phonon frequencies associated with the vibrations of the H atoms are not too hard, this result could lead to a sizeable electron-optical-phonon coupling in this material.