v 1 2 1 D ec 1 99 4 First - Principles Determination of Chain - Structure Instability in KNbO 3
نویسنده
چکیده
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 a 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. Submitted to Phys. Rev. Lett. 77.80.-e, 63.20.-e, 64.60.-i Typeset using REVTEX
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