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                                                                        has reported the moduli of quite a good range of radii and our results show the same trends. Experiments have shown that Y of CNTs is in order of 1Tpa. [13, 18-21]. In addition to the resistance to yield and fracture [22] Young's modulus Y can be used to measure the strength of materials and great number of works have been devoted to determining the Young's Modulus of CNTs using the empirical MD [11, 23-27], tight binding [28-30] or ab initio [31-33]. The value of Poisson ratio is 0. 28 as reported by Lu [11] and 0. 19 by Yakobson et al using Tersoff- Brenner potential [34]. Using finite element method, Sun et. al. [35] have calculated the value of Poisson ratio to lie in the range of 0. 31 to 0. 35. Our values of Poisson ratio for (5, 5), (10, 10), (8, 4), (12, 6) nanotubes match well with ref [10] but our values are higher for (9, 0) and (17, 0) nanotubes and match well with ref [11]. The shear Modulus for CNTs lies in the range of 300 Gpa. Our value of shear modulus for (5, 5), (10, 10), (9, 0), (17, 0), (8, 4), (12, 6), (20, 10) matches well with S. Gupta et. al. [10]. Values calculated by J.P. Lu [11] for shear modulus are little higher. Our results for shear modulus are in good agreement with ref [36]. The second generation reactive empirical bond order (REBO) potential with modified parameters reproduces the Y values, Poisson's ratios n and Shear Modulus G for CNTs. We look forward to others also to check the validity of this potential for other nanostructures as well. Acknowledgements: Authors are thankful to Dr. H.S. Bhatti, Professor and Head, Department of Physics, Punjabi University, Patiala for guiding and providing necessary facilities to bring this work in the present form. References.
                                                                    
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