A procedure is proposed enabling the substitution of a translationally non-invariant one-dimensional structure with unequal neighbouring spacing by a statistically equivalent ideal structure with equal spacing between neighbouring molecules. A procedure of statistical averaging of the...

The exciton states in a film which was cut out from an anisotropic cubic structure are analysed whereby the calculations include excitonic concentrations. It is shown that excitonic states in the bulk always exist, without any additional conditions on the type of the deformation or on exciton...

The possibility of the existence of undamped kinematical excitations in one-dimensional molecular crystals is examined. It is shown that such excitations exist although not for all wave vector values in the first Brillouin zone but only in the interval -2π5⩽ka⩽2π5. It is found that for the...