OICC Press Journal of Nanostructure in Chemistry 2193-8865 9 1 (March 2019) 2019 02 13 A DFT study on N-6-amino-hexylamide functionalized single-walled carbon nanotubes in interaction with silver ion in a gaseous environment 10.1007/s40097-019-0296-7 EN Khoorshid Mehdizadeh Department of Chemistry, Roudsar And Amlash Branch, Islamic Azad University, Roudsar, IR Masoud Giahi Nanotechnology Research Center, South Tehran Branch, Islamic Azad University, Tehran, IR Department of Chemistry, Faculty of Science, Lahijan Branch, Islamic Azad University, Lahijan, IR Journal Article 2019 02 13 Abstract In this study, quantum mechanical calculations, such as density functional theory (DFT), have been employed to determine the active positions of nanosensor and thermodynamics functions of interaction between Ag + and nanosensor have been calculated. HOMO and LUMO energies and energy difference between donor atoms ( i ) and acceptor atoms ( j ) have been evaluated. In addition, the effect of the number of substitution agents on the reactivity of the functional carbon nanotubes and the charge on the interacting atoms and Ag + before and after interaction have been investigated. The geometry optimization and theoretical calculations have been carried out using B3LYP level of theory. Results show that the interaction of Ag + with nanosensor is in terms of thermodynamically possible. The negative values of Δ G° denote a spontaneous reaction and the negative values of Δ H° represent an exothermic reaction. In addition, the nanosensor has two active positions and the product obtained through the interaction between Ag + and oxygen of the carbonyl group is the most stable state. The interaction of Ag + with the nanosensor is accompanied by a reduction in the energy gap ( E g ) which increases the stability of the complex, causes indicating that a charge transfer occurred between the nanosensor and Ag + .