From: Nicola Marzari <marzari@dave.nrl.navy.mil> Date: Tue, 9 Mar 1999 19:40:40 GMT (64kb)
Authors:
Nicola Marzari (1),
David Vanderbilt (1),
Alessandro De Vita (2),
M.C. Payne (3) ((1) Department of Physics and Astronomy, Rutgers University, (2) INFM and Department of Material Engineering and Applied Chemistry, University of Trieste, (3) Cavendish Laboratory (TCM), University of Cambridge)
Comments: 4 pages, two-column style with 5 PostScript figures embedded. Uses
RevTeX and epsf macros. To appear in Phys. Rev. Lett. Also available at
this http URL
Subj-class: Materials Science
Al(110) has been studied for temperatures up to 900 K via ensemble density-functional molecular dynamics. The strong anharmonicity displayed by this surface results in a negative coefficient of thermal expansion, where the first interlayer distance decreases with increasing temperature. Very shallow channels of oscillation for the second-layer atoms in the direction perpendicular to the surface support this anomalous contraction, and provide a novel mechanism for the formation of adatom-vacancy pairs, preliminary to the disordering and premelting transition. Such characteristic behavior originates in the free-electron-gas bonding at a loosely packed surface.