ENERGETICS, FORCES, AND QUANTIZED CONDUCTANCE IN JELLIUM-MODELED METALLIC NANOWIRES

Energetics and quantized conductance in jellium-modeled nanowires are investigated using the local-density-functional-based shell correction method, extending our previous study of uniform-in-shape wires [C. Ya nnouleas and U. Landman, J. Phys. Chem. B 101, 5780 (1997)] to wires c ontaining a variable-shaped constricted region. The energetics of the wire (sodium) as a function of the length of the volume-conserving, ad iabatically shaped constriction, or equivalently its minimum width, le ads to the formation of self-selecting magic wire configurations, i.e. , a discrete configurational sequence of enhanced stability, originati ng from quantization of the electronic spectrum, namely, formation of transverse subbands due to the reduced lateral dimensions of the wire. These subbands are the analogs of shells in finite-size, zero-dimensi onal fermionic systems, such as metal clusters, atomic nuclei, and He- 3 dusters, where magic numbers are known to occur. These variations in the energy result in oscillations in the force required to elongate t he wire and are directly correlated with the stepwise variations of th e conductance of the nanowire in units of 2e(2)/h. The oscillatory pat terns in the energetics and forces, and the correlated stepwise variat ion in the conductance, are shown, numerically and through a semiclass ical analysis, to be dominated by the quantized spectrum of the transv erse states at the most narrow part of the constriction in the wire. [ S0163-1829(98)01908-0].