The improvement of polycrystal diffraction structure of 7-ADCA was realized tby obtaining the X ray powder diffraction pattern within shorter time after carrying out improvement in probe, searching peaks automatically and indexing the pattern by Dicvol91, establishing the molecular model as a zwitterionic form, and refining the cell with more parameters. The results showed that compared to the previous work, the system, space group and unit cell parameters are nearly invariable, while the Rwp decreases from 14.95% to 7.78% because the fraction coordinate of each atom in the unit cell changes significantly. Finally, a better crystal structural model of 7-ADCA was obtained which can explain its growth characteristics reasonably.
