  Thermal conductivity of hadron matter is studied using a microscopic
transport model, which will be used to simulate ultra-relativistic heavy ion
collisions at different energy densities, namely the Ultra-relativistic Quantum
Molecular Dynamics (UrQMD). The molecular dynamics simulation is performed for
a system of light mesons species (pion, rho, kaon) in a box with periodic
boundary conditions. The equilibrium state is investigated by studying chemical
equilibrium and thermal equilibrium of the system. Particle multiplicity
equilibrates with time, and the energy spectra of different light mesons
species have the same slopes and common temperatures when thermal equilibrium
is reached. Thermal conductivity transport coefficient is calculated from the
heat current - current correlations using the Green-Kubo relations.
