Phonon modes in single-walled molybdenum disulphide nanotubes: lattice dynamics calculation and molecular dynamics simulation

• Published in: Nanotechnology 2014-03, Vol.25 (10), p.105706-9
• Main Authors: Jiang, Jin-Wu, Wang, Bing-Shen, Rabczuk, Timon
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Eigenvectors; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; lattice dynamics; Lattice vibration; Materials science; Mathematical analysis; Molecular dynamics; Molybdenum disulfide; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; nanotube; Nanotubes; phonon modes; Phonons; Physics; Structure of solids and liquids; crystallography; Thermal properties of condensed matter; Thermal properties of small particles, nanocrystals, nanotubes; Tubes
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/0957-4484/25/10/105706

We study the phonon modes in single-walled MoS2 nanotubes via lattice dynamics calculation and molecular dynamics simulation. The phonon spectra for tubes of arbitrary chiralities are calculated from a dynamical matrix constructed by the combination of an empirical potential with the conserved helical quantum numbers (κ, n). In particular, we show that the frequency (ω) of the radial breathing mode is inversely proportional to the tube diameter (d) as ω = 665.3 d cm−1. The eigenvectors of the twenty lowest-frequency phonon modes are illustrated. Based on these eigenvectors, we demonstrate that the radial breathing oscillation is initially disturbed by phonon modes of three-fold symmetry, then eventually the tube is squashed by modes of two-fold symmetry . Our study provides fundamental knowledge for further investigations of the thermal and mechanical properties of MoS2 nanotubes.