Open AccessPath‐integral approach to anharmonic vibration of solids and solid interfaces
Author(s) -
Yokoyama Toshihiko
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049500019014
Subject(s) - anharmonicity , vibration , materials science , anisotropy , path integral formulation , atom (system on chip) , extended x ray absorption fine structure , absorption (acoustics) , thin film , molecular physics , propagator , condensed matter physics , chemistry , absorption spectroscopy , physics , optics , composite material , quantum mechanics , quantum , nanotechnology , computer science , embedded system
The temperature dependence of EXAFS (extended X‐ray absorption fine structure) cumulants was investigated for bulk Cu and a thin film of Cu by means of the path‐integral effective classical potential method. By using the semi‐empirical embedded‐atom method as a potential, agreement between the experiments and calculations is found to be excellent for bulk Cu. In the thin Cu(111) film, anisotropic anharmonic vibration was clearly observed; the out‐of‐plane vibration is much more enhanced and more anharmonic than the lateral vibration. The results are semiquantitatively consistent with the previous experimental data on Cu(111)/graphite. Such a vibrational enhancement should be the driving force for the roughening transition and/or the surface pre‐melting at higher temperature. The practical usefulness of the path‐integral effective classical potential method combined with the embedded‐atom method is demonstrated.