Abstract
Structural, vibrational, and lattice dielectric properties of are studied using the density-functional theory within the local spin-density approximation, and the results are compared with those computed previously for Replacing Ca with Cd is found to leave many calculated quantities largely unaltered, although significant differences do emerge in zone-center optical phonon frequencies and mode effective charges. The computed phonon frequencies of are found to be in excellent agreement with experiment, and the computed lattice contribution to the intrinsic static dielectric constant also agrees exceptionally well with a recent optical absorption experiment. These results provide further support for a picture in which the lattice dielectric response is essentially conventional, suggesting an extrinsic origin for the anomalous low-frequency dielectric response recently observed in both materials.
- Received 9 September 2002
DOI:https://doi.org/10.1103/PhysRevB.67.012103
©2003 American Physical Society