A comprehensive ab initio investigation of the effects of the relative orientation(RO) between the adjacent tubes in a rope on the stability, structural, electronic,optical and Raman-active properties has been performed for the ropes of smalldiameter carbon (6, 6) nanotubes. A number of new features not discussedearlier are observed in the present study. The symmetric rope with an RO of0° is metallic in all directions, whereas the asymmetric ropes with a non-zerovalue of RO are semiconductors along the tube axis but semi-metallicnormal to rope axis. The band gap increases with RO up to an angle of15° and thereafter reveals oscillatory behaviour. No dips appear in the symmetricrope but they do exist in the asymmetric rope. Strong optical absorptionappears along the axis in the energy range 2.4–4.2 eV in the isolated tube. Onthe other hand, for the ropes, the strong absorption extends up to the energyregion 1.8–4.5 eV. Strong peaks also occur at 0.05 and 0.15 eV for the ropes withRO = 0° and15°, respectively.The even-parity Raman-active radial breathing mode (RBM) frequencies calculated here for the isolated(n,n), n = 3–6 tubes are seen to deviate from the usual law (where d is the tube diameter). For small diameter tubes, this shows an approximatevariation, ω = 1/d1/2.The RBM frequencies for the ropes are either greater or smaller compared to the isolatedtube, depending on the value of RO. A cubic anharmonicity of about 14% is seen in thepotential for the radial mode vibrations. The RBM frequencies calculated here for someropes, which are lower compared to that of the isolated tube, concur with the availableRaman data.