2000/08/23 by S. Koval, Koval, S., J. Kohanoff +5
Physics and Astronomy · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.cond-mat/0008340
8 pages, 2 postscript figures, submitted to the X Conference on Computational Materials Science, Villasimius, Sardinia (Italy), 2000
arxiv created 2000/08/23 · arxiv updated 2009/11/30
The origin of ferroelectricity in KH2PO4 (KDP) is studied by first-principles electronic structure calculations. In the low-temperature phase, the collective off-center ordering of the protons is accompanied by an electronic charge delocalization from the "near" and localization at the "far" oxygen within the O-H...O bonds. Electrostatic forces, then, push the K+ ions towards off-center positions, and induce a macroscopic polarization. The analysis of the correlation between different geometrical and electronic quantities, in connection with experimental data, supports the idea that the role of tunnelling in isotopic effects is irrelevant. Instead, geometrical quantum effects appear to play a central role.