Due to the unique physical properties (elasticity, stiffness and deformation) and the application in various materials (semiconducting, H2 storage) and the probes of nanotubes, they have attracted considerable attention. In order to investigate the physical properties of single walled nanotubes, it seems that theoretical analysis are necessary to determining the real nature of single walled nanotubes and specify their properties [1]. The geometrical structure of single walled silicon and boron-silicon nanotubes is a rolling up 2-D-semigraphite sheet as a hollow cylindrical shape [2]. According to the geometrical analysis, there exist armchair, zigzag and chiral tubular structures. Single walled nanotubes are n-bonded aromatic molecular that can be either semi conducting or metallic depending upon the tubular diameter and chirality. In this study the electronic and structural properties of single walled silicon nanotubes (n,0) zigzag for 7 ≤ n ≤ 10 and (n,n) armchair for 5 ≤ n ≤ 8 and single walled boron-silicon nanotubes (n,0) zigzag for 4≤n≤10 and (n,n) armchair for 4 ≤ n ≤ 8 with dangling bonds that saturated by hydrogen atoms have been investigated using density functional theory.
