Quadrupole plasmon excitations in finite-size atomic chain systems

• Published in: Physica. B, Condensed matter Vol. 454; pp. 165 - 169
• Main Authors: Wu, Reng-lai, Xue, Hong-jie, Yu, Yabin
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.12.2014; Elsevier
• Subjects: Chains; Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dipoles; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic systems; Exact sciences and technology; Excitation; One-dimensional; Physics; Plasmon; Plasmons; Quadrupole; Quadrupoles; Vibration; Quadrupole; Plasmon; One-dimensional; Finite size effect; Oscillations; Electron charge distribution; Time dependence; Atomic chain; Vibrational modes; Electron mobility; Density functional method; Plasmons; Quadrupole moments; One-dimensional systems; Collective excitations
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2014.07.078

The existence and the nature of a new mode of electronic collective excitations (quadrupole plasmons) in confined one-dimensional electronic systems, used to mimic finite-size linear metal atomic chains, have been predicted by an eigen-equation method. The eigen-equation based on the time-dependent density-functional theory is presented for calculating the collective excitations in confined systems. With this method, all modes of collective excitations in the 1D systems can be found out. These modes include dipole plasmons and quadrupole plasmons. The dipole plasmon mode corresponds to the antisymmetric oscillation of induced charge, and can be shown as a resonance of the dipole response. In the quadrupole plasmon modes, the induced charge distribution is symmetric, and the dipole response vanishes. The motion of the electrons in the quadrupole modes is similar to the vibration of atoms in the breathing mode of phonons. This type of plasmon can be shown as a resonance of the quadrupole response, and has to be excited by a non-uniform field.