Über den Einfluß von Gitterschwingungen auf Energie und Lebensdauer des Exzitons
The exciton is treated as a system of two particles which interact via Coulomb potential −e2/ɛ∞γ and are coupled to the quantized field of lattice vibrations. The ground state energy of the total system is calculated by means of a field theoretical variational method ofFeynman. The results are better than all those hitherto published which are obtained mostly as special cases, except the exact asymptotic solution at large distances, derived previously. By means of an extension ofFeynman's method which, however, invaliditates in general the variational principle, energies and lifetimes of excited states at temperaturesT>0° K are calculated.