Harmonic Fourier Beads (HFB) method is used for computing minimum free energy paths under finite temperature condition. This methoduses the Fourier representation of a path in an appropriate coordinate space. Molecular dynamics method is used to generate positions for the next path. Discrete path points are restrained by harmonic force field. Utilizing HFB method, we calculate the minimum free energy path of conformational change of carbon structures, which is among the rare event phenomena.