title: CoNTub v2.0--algorithms for constructing C3-symmetric models of three-nanotube junctions.
abstract: Here, a method is described for easily building three-carbon nanotube junctions. It allows the geometry to be found and bond connectivity of C(3) symmetric nanotube junctions to be established. Such junctions may present a variable degree of pyramidalization and are composed of three identical carbon nanotubes with arbitrary chirality. From the indices of the target nanotube, applying the formulas of strip algebra, the possible positions of the six defects (heptagonal rings) needed can be found. Given the multiple possibilities that arise for a specific pair of indices, the relation between the macroscopic geometry (interbranch angles, junction size, and pyramidalization) and each specific solution is found. To automate the construction of these structures, we implemented this algorithm with CoNTub software, version 2.0, which is available at ( http://www.ugr.es/local/gmdm/contub2 ). In addition, a classification of three-nanotube junctions, 3TJ, in seven types based on the location of defects has been proposed, i.e. 3TJ(0:0:6), 3TJ(0:1:5), 3TJ(0:2:4), 3TJ(0:3:3), 3TJ(1:1:4), 3TJ(1:2:3), and 3TJ(2:2:2) types.
authors.affiliation: Grupo de Modelización y Diseño Molecular, Departamento de Química Orgánica, Facultad de Ciencias, Granada, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Melchor
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Martin-Martinez
authors.forename: José A
authors.initials: JA
authors.lastname: Dobado
mesh_terms: D000465:Algorithms; D008958:Models, Molecular; D008968:Molecular Conformation; D037742:Nanotubes, Carbon / Q000737:chemistry*; D012984:Software; D013237:Stereoisomerism
chemical_list: D037742:Nanotubes, Carbon