A complete mapping in the Brillouin zone of the structural instability associated with the ferroelectric phase transitions of KNbO3 has been obtained by first-principles calculations using an LAPW linear response approach. The wavevector dependence of the instability reveals pronounced two-dimensional character, which corresponds to chains oriented along ⟨100⟩\ directions of displaced Nb atoms. The results are discussed in relation to models of the ferroelectric phase transitions.
@article{arxiv.mtrl-th/9412008,
title = {First-Principles Determination of Chain-Structure Instability in KNbO$_3$},
author = {Rici Yu and Henry Krakauer},
journal= {arXiv preprint arXiv:mtrl-th/9412008},
year = {2016}
}