Wall "thickness" effects on Raman spectrum shift, thermal conductivity, and Young's modulus of single-walled...

We demonstrate that at a finite temperature, an effective wall thickness of a single-walled carbon nanotube (SWNT) should be W = Ws + Wd, where Ws is the static thickness defined as the extension of the outmost electronic orbit and Wd the dynamic thickness due to thermal vibration of atoms. Both molecular simulations and a theoretical analysis show that Wd is proportional to T1/2. We find that the increase of dynamic thickness with temperature is the main mechanism of Raman spectrum shift. The introduction of the dynamic thickness changes some conclusions about Young's modulus and reduces the values of thermal conductivity.