Anomalously Large Thermal Expansion at the (0001) Surface of Beryllium without Observable Interlayer Anharmonicity

Journal Article · Sun Mar 01 00:00:00 EST 1998 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.80.2853· OSTI ID:599150

Pohl, K; Pohl, K; Plummer, E W; Plummer, E W ^[1]; Cho, J; Terakura, K ^[2]; Scheffler, M ^[3]

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1. Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200 (United States)
2. JRCAT, National Institute of Advanced Interdisciplinary Research, 1-1-4 Higashi, Tsukuba, Ibaraki 305 (Japan)
3. Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin-Dahlem, Germany; University of California at Los Angeles, Los Angeles, California 90024 (United States)

We have measured a large thermal surface expansion, 6 times larger than the bulk, on Be(0001) using low-energy electron diffraction. This observation seems to be inconsistent with previous measurements reporting negligible anharmonicity in the surface phonon modes normal to the surface. Density-functional theory calculations for the thermal expansion from the minimum in the free energy within the quasiharmonic approximation agree with the experimental observations and demonstrate that the enhanced thermal expansion is caused largely by a softening of the in-plane vibrations. {copyright} {ital 1998} {ital The American Physical Society}

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 599150
• Journal Information: Physical Review Letters, Vol. 80, Issue 13; Other Information: PBD: Mar 1998
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ELECTRON DIFFRACTION
BERYLLIUM
THERMAL EXPANSION
SURFACE PROPERTIES
PHONONS
MULTIPLE SCATTERING
DEBYE TEMPERATURE
RELAXATION
TEMPERATURE DEPENDENCE