The polypeptide is a kind of important biological molecule.Many peptides form protein by processing and deforming.Research on the stable conformation of the polypeptide is very important in the actual life.In order to explore the properties of stable conformation of polypeptide,we have studied the stable conformations of dipeptides and tripeptides of glycine and threonine,which is a good foundation for studying the conformation of biological macromolecule.The scan of the potential energy surface and the opt...