Color online. Left-hand side: according to the one dimensional model described in section, a single particle is formed by several carbon atoms lying on the same plane orthogonal to the CNT axis. Particles are linked by means of several carbon-carbon covalent bonds (not aligned with the CNT axis), with r0 denoting the spacing between particles at rest. Right-hand side: at low temperature, T <1000 K, small deviations from the rest position are observed so that the adopted potential (1) can be safely approximated by harmonic Taylor expansion about x = 0.
Chiavazzo and Asinari Nanoscale Research Letters 2011 6:249 doi:10.1186/1556-276X-6-249