@article{roland_bernholc_brabec_nardelli_maiti_2000, title={Theoretical investigations of carbon nanotube growth}, volume={25}, ISSN={["0892-7022"]}, DOI={10.1080/08927020008044108}, abstractNote={Abstract The growth of carbon nanotubes was investigated using a variety of complementary simulation techniques. Currently, a number of experimental methods are used to synthesize carbon nanotubes suggesting that different mechanisms play a role in their formation. However, it has been shown that growth of nanotubes takes place primarily at the open-ended tips of nanotubes. Ab initio simulations show that the high electric fields present at the nanotube tips in carbon arc discharges cannot be responsible for keeping the tubes open. Rather, the opening and closing of tubes is controlled by the formation of curvature-inducing defects such as adjacent pentagon pairs. On narrow tubes, the formation of such defects is favored leading to the rapid closure of the tubes. By contrast, the formation of hexagons, which lead to straight open-ended growth is favored on large-diameter tubes, with an estimated crossover radius of about 3 nm. Large-scale molecular dynamics and kinetic Monte Carle simulations have been used to verify these ideas. We have also explored the role of the so-called lip–lip interactions during growth. Such an interaction is important in producing multiwalled nanotubes, where the interaction between two open nanotube tips leads to the formation of a network of bonds. Simulations show that such an interaction is indeed significant, but does not provide the additional stabilization required for straight, open-ended, multiwalled nanotube growth. Finally, we consider the formation of nanotubes in the presence of large and small catalytic particles. In the former case, growth is believed to take place via a root-growth mechanism, while the direct adsorption and extrusion of carbon from the vapor dominates the latter. Both mechanisms lead to the formation of small-diameter, single-wall nanotubes.}, number={1-2}, journal={MOLECULAR SIMULATION}, author={Roland, C and Bernholc, J and Brabec, C and Nardelli, MB and Maiti, A}, year={2000}, pages={1–12} }
 @article{nardelli_brabec_maiti_roland_bernholc_1998, title={Lip-lip interactions and the growth of multiwalled carbon nanotubes}, volume={80}, DOI={10.1103/physrevlett.80.313}, abstractNote={Using a realistic many-body potential, we have simulated the properties of double-walled carbon nanotubes with the aim of investigating the role of lip-lip interactions on nanotube growth. Surprisingly, the lip-lip interaction by itself does not stabilize open-ended growth, but rather facilitates tube closure by mediating the transfer of atoms between inner and outer shells. A simulation of growth on a wide double-wall nanotube leads to considerable deviations from the ideal structure, in contrast to corresponding simulations for single-wall tubes, which result in nearly perfect structures. [S0031-9007(97)04989-2]}, number={2}, journal={Physical Review Letters}, author={Nardelli, M. B. and Brabec, C. and Maiti, A. and Roland, C. and Bernholc, Jerzy}, year={1998}, pages={313–316} }
 @article{bernholc_brabec_nardelli_maiti_roland_yakobson_1998, title={Theory of growth and mechanical properties of nanotubes}, volume={67}, ISSN={["1432-0630"]}, DOI={10.1007/s003390050735}, number={1}, journal={APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING}, author={Bernholc, J and Brabec, C and Nardelli, MB and Maiti, A and Roland, C and Yakobson, BI}, year={1998}, month={Jul}, pages={39–46} }
 @article{yakobson_campbell_brabec_bernholc_1997, title={High strain rate fracture and C-chain unraveling in carbon nanotubes}, volume={8}, ISSN={["0927-0256"]}, DOI={10.1016/S0927-0256(97)00047-5}, abstractNote={Nanotube behavior at high rate tensile strain (~ 1 MHz) is studied by molecular dynamics using a realistic many-body interatomic potential. The simulatins performed for single- and double-walled nanotubes of different helicities, and at different temperatures, show that nanotubes have an extremely large breaking strain. It decreases somewhat with increasing temperature and smaller strain rate, while the influence of helicity is very weak. At later stages of fracture, the nanotube fragments are connected by a set of unraveling monoatomic chains. The chains 'compete' with each other for carbon atoms popping out of the original tube segments. The interaction between chains eventually leads to a single chain, which grows up to hundreds of atoms in length before its breakage.}, number={4}, journal={COMPUTATIONAL MATERIALS SCIENCE}, author={Yakobson, BI and Campbell, MP and Brabec, CJ and Bernholc, J}, year={1997}, month={Sep}, pages={341–348} }
 @article{maiti_brabec_bernholc_1997, title={Kinetics of metal-catalyzed growth of single-walled carbon nanotubes}, volume={55}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.55.r6097}, abstractNote={Molecular-dynamics and total-energy calculations using a realistic three-body potential for carbon reveal the basic atomic processes by which single-shelled nanotubes can grow out of metal-carbide particles by the root growth mechanism. We find that nanometer-sized protrusions on the metal-particle surface lead to the nucleation of very narrow tubes. Wide bumps lead to a strained graphene sheet and no nanotube growth. The results also explain the absence of multishelled tubes in metal-catalyzed growth. @S0163-1829~97!51210-0#}, number={10}, journal={PHYSICAL REVIEW B}, author={Maiti, A and Brabec, CJ and Bernholc, J}, year={1997}, month={Mar}, pages={R6097–R6100} }
 @article{bernholc_briggs_sullivan_brabec_nardelli_rapcewicz_roland_wensell_1997, title={Real space multigrid methods for large scale electronic structure problems}, volume={65}, DOI={10.1002/(SICI)1097-461X(1997)65:5<531::AID-QUA18>3.0.CO;2-5}, abstractNote={We describe the development and applications of a new electronic structure method that uses a real-space grid as a basis. Multigrid techniques provide preconditioning and convergence acceleration at all length scales and therefore lead to particularly efficient algorithms. The salient points of our implementation include: (i) new compact discretization schemes in real space for systems with cubic, orthorhombic, and hexagonal symmetry and (ii) new multilevel algorithms for the iterative solution of Kohn–Sham and Poisson equations. The accuracy of the discretizations was tested by direct comparison with plane-wave calculations, when possible, and the results were in excellent agreement in all cases. These techniques are very suitable for use on massively parallel computers and in O(N) methods. Tests on the Cray-T3D have shown nearly linear scaling of the execution time up to the maximum number of processors (512). The above methodology was tested on a large number of systems, such as the C60 molecule, diamond, Si and GaN supercells, and quantum molecular dynamics simulations for Si. Large-scale applications include a simulation of surface melting of Si and investigations of electronic and structural properties of surfaces, interfaces, and biomolecules. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65: 531–543, 1997}, number={5}, journal={International Journal of Quantum Chemistry}, author={Bernholc, Jerzy and Briggs, E. L. and Sullivan, D. J. and Brabec, C. J. and Nardelli, M. B. and Rapcewicz, K. and Roland, C. and Wensell, M.}, year={1997}, pages={531–543} }