Condensed Matter, abstract
cond-mat/0209208
From: David Vanderbilt <dhv@physics.rutgers.edu>
Date: Mon, 9 Sep 2002 19:23:03 GMT (10kb)
Lattice dielectric response of CdCu{3}Ti{4}O{12} and of
CaCu{3}Ti{4}O{12} from first principles
Authors:
Lixin He,
J.B. Neaton,
David Vanderbilt,
Morrel H. Cohen (Department of Physics and Astronomy, Rutgers University)
Comments: 5 pages; uses REVTEX macros. Also available at
this http URL
Subj-class: Materials Science
Structural, vibrational, and lattice dielectric properties of
CdCu{3}Ti{4}O{12} are studied using density-functional theory within the local
spin-density approximation, and the results are compared with those computed
previously for CaCu{3}Ti{4}O{12}. 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 CdCu{3}Ti{4}O{12} are found to be in
excellent agreement with experiment, and the computed lattice contribution to
the intrinsic static dielectric constant (~60) 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.