In this research, the interactions of HCN gas with pristine, Ga-, N- and GaN-doped of boron phosphide nanotube (BPNTs) were investigated by using density function theory (DFT). The structure, electrical and NQR parameters, quantum descriptors involving energy gap, global hardness, global softness, electrophilicity, electronic chemical potential and electronegativity were calculated. The adsorption energy values of the AI-BIV models were negative and the adsorption process was exothermic. GaN-doped impurity atoms increased the adsorption of HCN gas on the surface of nanotube and the GaN-doped model was favorable than other models. The NQR parameters of the fourth layer of pristine and N-doped models were more than those of other models due to the change of the geometrical parameters. The energy gap between LUMO and HOMO orbital changed slightly from 2.83-3.09 eV, with adsorption of HCN gas on the surface of BPNTs. The global hardness and ionization potential and natural charge of NBO calculations showed a charge transfer from the HCN molecule
