  We theoretically investigate physical properties of the pressure-induced
activation volume and dynamic decoupling of ternidazole, glycerol, and probucol
by the Elastically Collective Nonlinear Langevin Equation theory. Based on the
predicted temperature dependence of activated relaxation under various
compression, the activation volume is determined to characterize effects of
pressure on molecular dynamics of materials. We find that the decoupling of the
structural relaxation time of compressed systems from their bulk uncompressed
value is governed by the power-law rule. The decoupling exponent exponentially
grows with pressure below 2 GPa. The decoupling exponent and activation volume
are intercorrelated and have a connection with the differential activation free
energy. We numerically and mathematically analyze relationships among these
quantities to explain many results in previous experiments and simulations.
