  A theory is developed to calculate values of the potential energy barriers to
structural relaxation in molecular glass formers from the data of static pair
correlation function. The barrier height is shown to increase due to increase
in number of the stable bonds a particle forms with its neighbours and energy
of each bond as liquids move deeper into the supercooled (super-compressed)
region. We present results for a system of hard-spheres and compare calculated
values of the structural relaxation time with experimental and simulation
results.
