Table 9: First free frequencies of vibrations of DWCNTs with different boundary conditions between inner and outer tubes, (for ).

Boundary conditionMethod

Fr-Fr inner[15]1.0402.845.1407.8908.1308.3809.350
Cl-Cl outerCDM1.0212.7865.7606.2706.6697.9158.083

Fr-Fr inner[15]0.1701.0402.8905.2906.5507.8908.170
Cl-Fr outerCDM0.1631.0242.8335.2106.4917.8608.041

SS-SS inner[15]1.0502.8405.1807.2907.8908.2409.080
Cl-Cl outerCDM1.02192.7895.1047.2127.9148.2439.010

Cl-Cl inner[15]1.0802.9405.4907.9008.1308.240
Cl-Cl outerCDM1.0582.8815.3947.9258.008.2559.400
R-S1.061