Peierls-type instabilities in quarter-filled ((n) over bar = 1/2) and half-
filled ((n) over bar = 1) quantum double-well hydrogen-bonded chain are inv
estigated analytically in the framework of two-stage orientational-tunnelli
ng model with additional inclusion of the interactions of protons with two
different optical phonon branches. It is shown that when the energy of prot
on-phonon coupling becomes large, the system undergoes a transition to vari
ous types of insulator states. The influence of two different transport amp
litudes on ground-state properties is studied. The results are compared wit
h the pressure effect experimental investigations in superprotonic systems
and hydrogen halides at low temperatures.