Radial polarons in carbon nanotubes

We use ab initio total-energy calculations to predict the existence of radial polarons in semiconducting carbon nanotubes (CNTs). We find that the CNTs' band edges vary linearly and the elastic energy increases quadratically with an applied radial, breathing-mode-like distortion. This leads to the spontaneous formation of polarons. Using a continuum model parametrized by the ab initio calculations, we estimate electron and hole polaron lengths, energies and effective masses and explain their dependence on CNT radius.