B3LYP/6-31G(d) DFT calculations of static first hyperpolarizability (beta) were performed for armchair (5,5) single wall carbon nanotube (CNT) functionalized with diethynylsilane (PDES) oligomers having electrondonor (D) or acceptor (A) groups attached to their ends. PDES oligomers were introduced longitudinally and transversely to the CNT external surface. Remarkable b values were obtained for all substituted CNT (>2000 x 10(-30) cm(5) esu(-1)). Furthermore, all chemically modified CNT presented very large polarizability values and very small HOMO-LUMO energy gap, indicating their possible use as conducting materials. Our results demonstrated that CNT hybrid materials containing Si might be promising applied in optoelectronics and photonics. (C) 2011 Elsevier B.V. All rights reserved.