Anisotropy of the proton kinetic energy in CsH2PO4 and KH2PO4

作者：Finkelstein Y^*; Moreh R; Shchur Ya

来源：Surface Science, 2018, 668: 112-116.

DOI：10.1016/j.susc.2017.10.028

• Proton
• Atomic kinetic energy
• Hydrogen bond
• KH2PO4, CsH2PO4
• Lattice dynamics
• Deep-inelastic neutron scattering
• Vibrational density of states

The strong anisotropy of the proton mean kinetic energy, Ke(H), in a single crystal of KH2PO4 (KDP), measured by deep inelastic neutron scattering (DINS), is compared with that calculated for its Cs analogue, CsH2PO4 (GDP) in the ferroelectric (FE) and paraelectric (PE) phases. Empirical lattice dynamics (LD) calculations were used to simulate the partial vibrational density of states shared by the protons (H-VDOS), from which Ke(H) values were deduced. Good agreement was found between the measured and calculated Ke(H) values of the two samples despite the different hydrogen bond dynamics. However, the directional components of Ke(H) in the two samples were quite different. In both cases, the Ke(H) tensor is nearly an ellipsoid of rotation: in KDP the shape is oblate around the major axis while being prolate in CDP. By resolving the directional Ke(H) values of the two non-equivalent protons of CDP, a possible signature of competing quantum effects is indicated.

• 出版日期2018-2