  We develop the elastically collective nonlinear Langevin equation theory of
bulk relaxation of glass-forming liquids to investigate molecular mobility
under compression conditions. The applied pressure restricts more molecular
motion and therefore significantly slows-down the molecular dynamics when
increasing the pressure. We quantitatively determine the temperature and
pressure dependence of the structural relaxation time. To validate our model,
dielectric spectroscopy experiments for three rigid and non-polymeric
supramolecules are carried out at ambient and elevated pressures. The numerical
results quantitatively agree with experimental data.
