Influence of Defects on Vibrational Characteristics of Linear Chains of Inert Gases Atoms Adsorbed on Carbon Nanobundles

Abstract

The study of vibrational characteristics of chains of rare gas atoms adsorbed in the grooves between nanotubes in nanobundles is reduced to the analyses of the phonon spectrum and the vibrational characteristics of linear chains of atoms in an external field. Atoms in the chain have three degrees of freedom. The analytical expressions for the vibrational characteristics of the atoms in the chain, depending on the ratio between the interatomic distance in the chain r and the equilibrium distance between atoms in the chain $r_0$, are obtained. It is shown that at $r<r_0$, the parameter of interatomic interaction, which determines the transverse vibrations frequencies, is negative. As a result, while the quasi-continuous spectrum band shifts to lower frequencies, the linear part of the temperature dependence of the heat capacity shifts to lower temperatures. The distance within only one pair of atoms is modified. It is the defect that can entail discrete states split off from the quasi-continuous spectrum band. The discrete levels with frequencies below the quasi-continuous spectrum band shift the linear part of the temperature dependence of the heat capacity to lower temperatures. The conditions for appearing of discrete frequency levels are obtained, and their characteristics are found.