Structural phase diagram and electron-phonon interaction in Ba1-xKxBiO3.

Liechtenstein A.I., Mazin I.I., Rodriguez C.O., Jepsen O., Andersen O.K., Methfessel M.

Using the local-density approximation and the full-potential linear muffin-tin-orbital method the authors have calculated the total energy of Ba1-xKxBiO3 for x=0 and 0.5 as a function of tilting and breathing distortions. For x=0 they find an instability for a combination of both distortions and they correctly reproduce the monoclinic structure. For x=0.5 the authors correctly find the cubic phase to be stable. The frequencies of the tilting and breathinglike phonons are calculated for x=0 and 0.5. In the cubic structure they calculate the strength lambda b of the electron-phonon coupling for the breathing mode as a function of x using a rigid-band approximation. For 0.37 

Physical Review B, 44 5388-91, 1991.

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