Resonanzaufspaltung im Schwingungsspektrum des CaSO4·2H2O
The resonance- or Davydov- or correlationfield-splittings of the vibrational levels of CaSO4·2H2O (gypsum) are calculated using the exciton theory ofDavydov. This theory is extended to include the induced polarization of crystalline matter by the electric fields of the transition dipoles.The numerical calculations are based on an experimental determination of the transition dipole moments and on a calculation of the dipole lattice sums by the Ewald method.The results obtained show, that in most cases the assumption of Coulomb interaction between transition dipoles alone does not completely explain the observed splittings. However, the shift of transition frequency with an increasing longitudinally polarized component of a polar crystal vibration can be predicted by this theory within the limits of accuracy of the experimental determination of transition moments.