Deuteration removes quantum dipolar defects from KDP crystals  

作　　者：Bingjia Yang Pinchen Xie Roberto Car 

机构地区：[1]Department of Chemistry,Princeton University,Princeton,NJ 08544,USA [2]Program in Applied and Computational Mathematics,Princeton University,Princeton,NJ 08544,USA [3]Department of Chemistry,Department of Physics,Program in Applied and Computational Mathematics,Princeton Materials Institute,Princeton University,Princeton,NJ 08544,USA

出　　处：《npj Computational Materials》2024年第1期684-693,共10页计算材料学(英文)

摘　　要：Dielectric properties of the hydrogen-bonded ferroelectric crystal KH_(2)PO_(4)(KDP)differ significantly from those of KD_(2)PO_(4)(DKDP).It is well established that deuteration affects the interplay of hydrogenbond switches and heavy ion displacements that underlie the emergence of macroscopic polarization,but a detailed microscopic model is missing.We show that all-atompath integral molecular dynamics simulations can predict the isotope effects,revealing the microscopic mechanism that differentiates KDP and DKDP.Proton tunneling generates phosphate configurations that do not contribute to the polarization.At low temperatures,these quantum dipolar defects are substantial in KDP but negligible in DKDP.These intrinsic defects explain why KDP has lower spontaneous polarization and transition entropy than DKDP.The prominent role of quantum fluctuations in KDP is related to the unusual strength of the hydrogen bonds and should be equally important in other crystals of the KDP family,which exhibit similar isotope effects.

关 键 词：QUANTUM KDP REMOVE 

分 类 号：O78[理学—晶体学]