1992    
1993    
1994    
1995    
1996    
1997    
1998    
1999    
2000    
2001    
2002    
2003    
2004    
2005    
2006    
2007    
2008    
2009    
2010    
2011    
2012    
2013    
2014    
2015    
2016    
Marcus, P. M., Qian, X., Qian, X. H., Hübner, W.

Properties of the surface region of a metal crystal
Journal of Physics C 13, (18),pp 3977-3985 Institute of Physics and IOP Publishing Limited, (2001)
Total-energy calculations from first principles have been made on a seven-atomic- layer slab of Mo(001) as a function of the in-plane lattice parameter with full relaxation of the layer spacings. The energy minimum gives the equilibrium state of the slab, which contracts both in plane and out of plane between one and two per cent with respect to bulk. The energy changes under deformation from equilibrium are treated as strain energies and are fitted to a composite elastic model consisting of two surface regions and a bulk region, each with its structural and elastic parameters. These parameters are evaluated in a separate calculation for the bulk region, so that subtracting the known bulk strain energies from the total strain energy permits evaluation of the parameters of the surface region. Six deformations of the slab around equilibrium give the six elastic constants of the tetragonal surface regions. The surface region material is about two atomic layers deep, slightly prolate in its own equilibrium state, substantially elastically anisotropic compared to cubic symmetry, stable, but considerably weaker elastically and closer to instability than bulk.

ki-2001-p01