Surface energy calculation of alkali metals with the empirical electron surface model

The empirical electron surface model (EESM) based on empirical electron theory (EET) and dangling bond analysis method has been used to establish a database of surface energy for low index surfaces of alkali metals such as Li, Na, K, Rb and Cs. Since the lattice electrons of alkali metals occupy large proportion of the total electron number for valence shell, the contribution of these lattice electrons cannot be neglected in surface energy calculation. Therefore, the necessary modification to EESM will be presented in this paper. The calculated results are in agreement with experimental and other theoretical values. And the calculation results show that the surface energy is anisotropic. As we predicted, the surface energy of the close-packed plane (1 1 0) is the lowest one of all index surfaces. It is also found that the dangling bond electron density and the spatial distributions of lattice electron have great influences on surface energy of various index surfaces. EESM will provide one good basis for the research of surface science phenomena, and since abundant information about valence electronic structure is generated from EET, the model may be extended to the surface energy estimation of more metals, alloys, ceramics and so on.