| Abstract: | A molecular theory of the piezoelectric constant of the α-helical backbone of polypeptide is developed on the basis of fluctuation formalism. The piezoelectric constant, electric susceptibility, and elastic compliance of the α-helix are calculated through the method of molecular lattice dynamics by use of normal-coordinate analysis. Displacements of each atom due to the external stress exerted upon the backbone are also calculated. The piezoelectricity of the α-helix is concluded to arise mainly from rotation of the CO? NH bond. The value of the piezoelectric constant of poly(γ-benzyl-L-glutamate) film calculated from the above theoretical constants along with a composite theory is found to agree reasonably with experiment. |
