Polarization Dependence of Born Effective Charge and Dielectric Constant in KNbO${}_3$

Cheng-Zhang Wang, Rici Yu, Henry Krakauer

The Born effective charge Z^{*} and dielectric tensor ε_{\infty} of KNbO_3 are found to be very sensitive to the atomic geometry, changing by as much as 27% between the paraelectri…