Theoretical study of doping carbon nanotubes with transition metals Brito, G. S.1, Vargas, M. R1, Santos, J.D1, Martins, J.B.L2, Taft, C.A3, Longo, E4 1 Universidade Estadual de Goiás, UnUCET, GO, Brazil 2 Universidade de Brasília, Brazil 3 Centro Brasileira de Pesquisas Físicas, Rio de Janeiro, RJ, Brazil 4 ,Universidade Estadual Paulista - Araraquara, SP, Brazil Carbon nanotubes have mechanical and electronic properties which can be used , for example, for gas sensors and conductors. This a particularly attractive possibility for the development of carbon structures, such as doped nanotubes with transition metals for catalytical applications [1, 2]. In this work theoretical calculations were made using the semi-empirical MNDO and ab initio B3LYP/6-31G method in carbon nanotubos with substitutional doping. The structures analyzed were the zigzag configuration (8,0) as well as armchair, (4,4), each with fived levels. Doping was made with Fe, Ti, Ni substituting carbon atoms in the extremities and middle of the nanotubes. In Fig. 1 is represented the doped nanotubes with Fe atoms in both extremities and in the middle. The results obtained were analyzed in relation to charge distribution, |HOMO-LUMO| differences and bond distances. Figura 1: Carbon nanotube model doped with Fe in both extremities and in the middle Keywords: Carbon nanotubes, substitutional doping.  STOYANOV, S. R.; TITOV, A. V.; KRÁL, P. Coordination Chemistry Review , v. 253, 2009.  STOYANOV, S. R.; KRÁL, P. The Journal of chemical physics, v. 129, 2008. e-mail: [email protected]; Adress: Br 153, nº 3.105,Fazenda Barreiro do Meio CEP: 75132-903 Caixa Postal: 459, Anápolis-Goiás.