Surface Characteristics of Alkali Metals with the Discrete Lattice and Friedel Oscillations of the Electron Density

The study makes an attempt to describe the effect of the crystal lattice on the surface characteristics of alkali metals in the framework of the density functional method. In the first approximation the real potential of the crystal lattice has been replaced by the potential of a homogeneous positive background (the jellium model). We calculated the difference between the discrete-ions potential and the potential of jellium in the framework of the perturbation theory. To calculate the impact of electron-ion interaction on the energy characteristics of the surface, the real potentials of ions were approximated by Ashcroft pseudopotential. The electron density in the inhomogeneous electron gas near the surface was approximated by trial distribution functions which take into account Friedel oscillations and lattice effects. Furthermore, we carried out self-consistent calculation of the surface energy taking into account the gradient expansion for the kinetic energy. In this paper, we defined surface characteristics, such as the work function and the potential barrier height and constructed effective potentials for alkaly metals. All the characteristics of the metal surface were calculated within the density functional method.

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