(BUT-bound), our dissociation rate was 104.47 × 10 2 s )* , whereas that of the earlier work was 45 × 10 2 s )* . As shown in Table , our dissociation rates significantly corresponded with the rates in an earlier study, with a small error factor. Additionally, we showed the dissociation times of the FKBP systems with different force fields: CHARMM 22 (CMAP) and SwissParam (Table ). We found that the resultant dissociation times for each system were slightly shorter than those for Amber ff99SB-ILDN (Figure and Table ). Further, we estimated the dissociation times without a constant force using the Bell's and DHS models (Figure and Table ). We observed the same trend in the dissociation times, as shown in Table . This implies that the choice of the two force fields did not affect the trend of the dissociation rates; however, it slightly affected the absolute dissociation rates. Furthermore, we observed that the dissociation times under a strong force indicated a relative relationship between the dissociation times of the three ligands (Figure ). This implies that the selection of a large force can rapidly evaluate the relative dissociation times.