Figure 1. Optimized Structures of CNT and DNTs

The distance of carbon-dopant atom is found 1.811 Å for S-C, 1.467 Å for N-C and 1.560 Å for B-C compared with the distance of C-C band in simple CNT, 1.45 Å. These consequences are in accordance with X-Ray data and previous theoretical works in DNTs.^27,49 Also, the distance of dopant atom and carbon atom of CO (X-C(CO)) in parallel (p) and perpendicular configurations (d) of CNT and DNTs are between 1.136-3.365 Å and 1.952-4.035 Å respectively. Therefore, these values demonstrate that the CO molecule will have better interaction in p configurations.