  Thermal conductivity of a model glass-forming system in the liquid and glass
states is studied using extensive numerical simulations. We show that near the
glass transition temperture, where the structural relaxation time becomes very
long, the measured thermal conductivity decreases with increasing age. Secondly
the thermal conductivity of the disordered solid obtained at low temperatures
depends on the cooling rate with which it was prepared, with lower cooling
rates leading to lower thermal conductivity. Our analysis links this decrease
of the thermal conductivity with increased exploration of lower-energy inherent
structures of the underlying potential energy landscape. Further we show that
the lowering of conductivity for lower-energy inherent structures is related to
the high frequency harmonic modes associated with the inherent structure being
less extended.
