DEFORMATION OF MOLECULAR CRYSTALS AT ELECTRONIC EXCITATION

In this article an investigation is made of deformation of the molecular crystal due to electronic excitation. It is shown that in a three‐dimensional crystals at a sufficiently large resonance interaction between molecules the states of free excitations with positive effective mass correspond to minimum of the total energy of the crystal. The transition to local excitations requires activation energy. The states of the free excitons with negative effective masses in three‐dimensional and one‐dimensional crystals are unstable. Exciton states with positive effective masses in one‐dimensional crystals are represented as modulated plane waves. Distribution of the excitation along some length of the crystal corresponds to these waves. The stronger is the resonance interaction between molecules, the more is this length. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim