Solvent and temperature-dependent conductive behavior of poly(3-hexylthiophene) Original Research Article

The electronic optical spectra of the mechanically free and stressed crystals of potassium sulfate, K2SO4, in the orthorhombic phase Pnma have been calculated by the Cambridge Serial Total Energy Package (CASTEP) code. On the basis of these calculations, the components of stress elasto optical tensors based on the changes of refractive index n (πim ) and birefringence Δn (View the MathML sourceπkm*) (i, k, m=1, 2, …, 6) have been obtained for the indices i, k ,m=1, 2, 3. Absolute magnitudes of the calculated tensor πim are probably underestimated because the magnitudes of the calculated elastic stiffness tensor crm are found to be overestimated about two times. Features of the spectral dependences n(E) and k(E) of refractive and absorption indices of the mechanically free and stressed potassium sulfate crystals have been analyzed.