The instantaneous vibrational frequency of
in argon solvent confined by single walled carbon nanotube
(SWNT) has been calculated by the mixed quantum‐classical molecular dynamics simulations. The variations of vibrational line shift with the tube radius are obtained to investigate the confinement effect. The results show that the frequency shifts for the confined systems are slightly blueshifted compared to the bulk system. Moreover, the shift moves to stronger blue as the tube radius increases. In addition, the mechanistic information correlating the shifts to solvent configurations, geometry confinement is explored at an atomic/molecular level.