Quantum size effects in finite metallic whiskers

The size dependence of the electronic density of states, Fermi energy, and the ionization potential of finite metallic whiskers is systematically inve stigated in a free-electron, finite-potential well model for Au and Al. Ani sotropy of work function is discussed. A nanowire is modeled by the uniform conductor of finite length and square cross section. Simple approach based on the dependence of the Fermi wavenumber on the depth of square potential well allows to obtain a correct monotonous size-dependence of the ionizati on potential relative to its bulk value. It is shown that the ionization po tential, as a function of the whisker radius, oscillates around this averag e dependence. These oscillations in the energetic and force properties resu lt from the size quantization of the energy levels. We obtained the force f luctuations in accordance with the experimentally found values. The consequ ences of the present investigation of the correct amount of force and condu ctance fluctuation in elongation of point contacts are discussed.