Gm. Rignanese et al., First-principles study of structural, electronic, dynamical, and dielectric properties of zircon - art. no. 104305, PHYS REV B, 6310(10), 2001, pp. 4305
We investigate structural, electronic, dynamical, and dielectric properties
of zircon (ZrSiO4) within density-functional theory. The atomic structure
is fully relaxed and the structural parameters are found to differ by less
than 1.5% from the experimental data. The associated electronic band struct
ure and density of states are also presented. Using density-functional pert
urbation theory, we obtain the phonon frequencies at the center of the Bril
louin zone, the Born effective charge tensors, and the dielectric permittiv
ity tensors. The calculated phonon frequencies agree with the infrared and
Raman experimental values (rms relative deviations of 2.5%) when available,
while the silent modes are predicted to range between 119.6 and 943.3 cm(-
1). We compute the Born effective charge tensors, that are found to be quit
e anisotropic. The electronic and static dielectric permittivity are analyz
ed in detail. Their difference is mostly due to the lowest infrared-active
mode, whose eigenvector corresponds to a distortion of the SiO4 tetrahedra
with a displacement of Zr and O atoms in opposite directions.