By using density functional theory (DFT) method in B3LYP on the 6-311 + G (d,p) basis set level,we have researched the geometric structure optimization,frequency analysis,infrared spectroscopy,natural charge population,the NBO analysis,the molecular energy and frontier orbital the calculation of energy about glucose,pyranose fructose,furfuran fructose,D-marigold synanthrin.The results has shown the activity order was:furfuran fructose >pyranose fructose > glucose > synanthrin.We have found that synanthrin's chemical potential was more...