Abstract
The lattice dynamics and superconductivity of face-centered cubic (fcc) La under pressure areextensively studied using the linear-response methods within the framework of density-functionaltheory. A pressure-induced softening transverse acoustic (TA) phonon mode at the L pointof the Brillouin zone is identified and the phonon softening pressure was predicted to be∼4.92 GPa, which coincides with the experimentally observed second-order phase transition pressure of∼5.3 GPa from fcc to distorted fcc. Moreover, no elastic instability is found undercompression. Analysis of the calculated results suggests that the TA phononinstability is the driving force for this second-order phase transition. Furthermore,the current electron–phonon coupling (EPC) calculations suggest that theexperimental observation of elevated superconducting transition temperatureTc with pressure is from the increased EPC strength and the softening TA phonon.
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