The interplay of short-range and long-range interactions between electrons (holes), defects and phonon fields was described in terms of a continuum model in which acoustic and optic phonon modes were replaced by elastic and dielectric media, respectively. By applying the variational principle to the adiabatic energy, it was possible to obtain phase diagrams for the stable and metastable states of the defect-bound electrons in the phonon field on the coordinate plane of short-range and long-range coupling constants. The metastability appeared when the short-range coupling was moderate, but dominated the long-range coupling. The electrical, optical and thermal behavior of electrons in various materials could be explained in terms of these phase diagrams.

Y.Toyozawa: Materials Science Forum, 1995, 196-201, 1-8