  The question is raised about the pressure effects on the polarizability and
dispersive binding in ionic and molecular systems. As an example we take the
effect of hydrostatic pressure on the energy gap of phonon-coupled two-level
systems. Assuming a positive pressure coefficient for the gap, we predict a
gradual transition from small vibronic polarons to large polarons as the
pressure is increased at constant coupling energy of a two-level system.
Concomitantly, the universal dispersive binding degrades from strong at low
pressure to weak at high pressure as the system evolves from soft condensed
matter to hard condensed matter. Implications are discussed on the development
of stellar substance at the early stages of the Universe.
