Exchange-correlation effects on low-dimensional plasmons in an array of metallic quantum wires

We investigate low-dimensional plasmons (PL's) in an array of metallic quantum wires. By developing a self-consistent local-field-correction (LFC) theory for treatment of the PL's in the wire array, we take account of both the intrawire exchange-correlation (XC) effect and the interwire correlation effect. By comparing the results involving the LFC with those in the random-phase approximation, we examine the XC effect on the energy distribution and the energy-loss intensity of all the PL modes in an array of a finite number of wires. Our theoretical scheme is applied to an array of Au-atom wires on the Si(557) surface. The XC effect is found to play a significant role because of strong one-dimensional confinement, though a high effective density of the electron system is suggestive of the free-electron-gas character. With an increase in wave number q, the XC effect operates to lower the mode energy increasingly, and to start the decline of the energy-loss intensity at smaller q values. In a smaller q range of qd less than or similar to 1, where d denotes the interwire separation, the interwire interaction has the mode energies separated from one another to form an energy distribution of considerable width. Our results of the XC effect and the effect of the interwire interaction yield general insights into the PL's in a variety of wire arrays.