SPECTRAL EFFECTS OF MICROSCOPIC AND MESOSCOPIC DISORDER IN ORGANIC FILMS — MODEL CALCULATIONS

Effects of microscopic orientational disorder on electro-absorption of charge-transfer (CT) states in the high-temerature phase of the C 60 crystal are simulated on a cluster consisting of 108 molecules. The results suggest that this kind of disorder may be successfully modeled in terms of an effective crystal with full translational symmetry. Mesoscopic disorder is simulated for thin films of sexithiophene. The spectral broadening observed in absorption is attributed to the non-analyticity of the calculated dipole sums at k=0, resulting in their dependence on crystallte orientation with respect to incident radiation.

Dipole oscillator strength properties and dispersion energy coefficients for H2S

Globally reliable dipole oscillator strength distributions (DOSDs) have been constructed for the H2S molecule in its ground state. An adopted DOSD is used to evaluate a variety of dipole oscillator strength sums Sk, logarithmic dipole sums Lk, and mean excitation energies Ik, for H2S; these dipole properties are important in various physical processes. It is also used to obtain reliable results for the dipole–dipole dispersion energy coefficients C6 for the interaction of H2S with itself, and with thirty-nine other atoms and (mostly) molecules, and the triple-dipole dispersion energy coefficient C9 for (H2S)3. A pseudo-DOSD for H2S is presented which facilitates the evaluation of C6's, and in particular C9's.

Dipole oscillator strength distributions, sums, and some related properties for Li, N, O, H2, N2, O2, NH3, H2O, NO, and N2O

Dipole oscillator strength distributions (DOSDs) have been constructed for ground state Li, N, O, H2, N2, O2, NH3, H2O, NO, and N2O by using experimental and theoretical photoabsoiption and high energy electron inelastic scattering cross sections. Each DOSD is required to satisfy the Thomas–Reiche–Kuhn sum rule and additional constraints derived from available accurate experimental refractivity and dispersion measurements. The DOSDs, the data and procedure used to construct the DOSDs, and the values of the dipole oscillator strength sums Sk and Lk (for a variety of k values) and related atomic and molecular properties obtained from the DOSDs are reported. The discussion includes comments regarding the importance of the constraints imposed on the DOSD with respect to the evaluation of various dipole sums and properties and the accuracy of the results.