ISSN:
1572-9605
Keywords:
YBa2Cu3O7
;
electronic band structure
;
LAPW method
;
density of states
;
Fermi surface
;
Coulomb potential
;
charge density
;
electron-phonon interaction
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
Notes:
Abstract Self-consistent linearized augmented plane wave (LAPW) method calculations of the band structure, density of states, Fermi surface, Coulomb potential, charge density, core-level shifts, and electron-phonon interaction are presented for Y1Ba2Cu3O7. The calculated Sommerfield parameterγ is 4.35 mJ(mole Cu)−1 K−2, roughly about a factor of 2 smaller than experimentally deduced values of the enhanced valueγ=(1 + λ)γ0, suggesting that the Fermi surface mass enhancement is of the order of unity. The crystal charge density is best represented by overlapping spherical ionic densities when the Cu and O ions are assigned charges of +1.62 and −1.69, respectively, corresponding to about 0.3 holes per oxygen atom. Core-level energies for the inequivalent atoms differ by as much as 0.45 eV for Cu and 0.7 eV for O, amounts which may be detectable by core-level spectroscopies. These results provide important information on the character and magnitude of ionic contributions to bonding in these materials. Within the rigid muffin-tin approximation, calculated McMillan-Hopfield parameters yield estimates for the electron-phonon strength λ that appear to be too small to account for the observedT c. We point out an unusual band of oxygen-derived chain states below, but within 0.1 eV of, the Fermi level.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00617955
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