The paper by Jijun Zhao, Alper Buldum, Jie Han, and Jian Ping Lu investigates the adsorption of various gas molecules (NO₂, O₂, NH₃, N₂, CO₂, CH₄, H₂O, H₂, Ar) on single-walled carbon nanotubes (SWNTs) and nanotube bundles using first principles methods. The study focuses on the equilibrium position, adsorption energy, charge transfer, and electronic band structures of these molecules. Most molecules adsorb weakly on SWNTs, acting as either charge donors or acceptors. The adsorption of certain gases, such as NO₂ and O₂, significantly affects the electronic properties of SWNTs, leading to charge transfer and fluctuation that can influence the transport properties of the nanotubes. The results are consistent with recent experimental findings, highlighting the importance of gas exposure in the behavior of carbon nanotubes. The study also compares the adsorption behavior on individual SWNTs and nanotube bundles, finding that the bundle interstitial and groove sites exhibit stronger adsorption compared to individual tubes.The paper by Jijun Zhao, Alper Buldum, Jie Han, and Jian Ping Lu investigates the adsorption of various gas molecules (NO₂, O₂, NH₃, N₂, CO₂, CH₄, H₂O, H₂, Ar) on single-walled carbon nanotubes (SWNTs) and nanotube bundles using first principles methods. The study focuses on the equilibrium position, adsorption energy, charge transfer, and electronic band structures of these molecules. Most molecules adsorb weakly on SWNTs, acting as either charge donors or acceptors. The adsorption of certain gases, such as NO₂ and O₂, significantly affects the electronic properties of SWNTs, leading to charge transfer and fluctuation that can influence the transport properties of the nanotubes. The results are consistent with recent experimental findings, highlighting the importance of gas exposure in the behavior of carbon nanotubes. The study also compares the adsorption behavior on individual SWNTs and nanotube bundles, finding that the bundle interstitial and groove sites exhibit stronger adsorption compared to individual tubes.