Excitonic instability

A second type of eigenstates, illustrated in Fig. 3.10, is the band of states formed by the exciton-contaminated photon continuum. Far from the critical area cK co0, this band presents a lorentzian resonance (cf. Fig. 3.9), whose temporal instability (cf. Fig. 3.8) is described by an exponential decay. Thus, the exact solution leads back to that of second-order perturbation theory, obtained in Section III.A.2.b above. 

Further possibilities for long-range effects of chemical carcinogens are provided by the change or occurrence of different collective states in these complex polymers. These collective states can be vibrational or conformational solitons, Mott insulator states, Peierls instabilities, plasmon-type states, charge and spin density waves, excitonic insulator states, etc. Here only one example (which has been worked out in some detail), namely a conformational soliton caused by carcinogen binding, will be discussed. 

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