TY - JOUR
T1 - Anisotropy of the proton kinetic energy in CsH2PO4 and KH2PO4
AU - Finkelstein, Y.
AU - Moreh, R.
AU - Shchur, Ya
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2018/2/1
Y1 - 2018/2/1
N2 - 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 (CDP) 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.
AB - 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 (CDP) 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.
KW - Atomic kinetic energy
KW - Deep-inelastic neutron scattering
KW - Hydrogen bond
KW - KHPO, CsHPO
KW - Lattice dynamics
KW - Proton
KW - Vibrational density of states
UR - http://www.scopus.com/inward/record.url?scp=85032827418&partnerID=8YFLogxK
U2 - 10.1016/j.susc.2017.10.028
DO - 10.1016/j.susc.2017.10.028
M3 - Article
AN - SCOPUS:85032827418
VL - 668
SP - 112
EP - 116
JO - Surface Science
JF - Surface Science
SN - 0039-6028
ER -