Thermal conductivity of diamond and related materials from molecular dynamics simulations

Based on the Green-Kubo relation from linear response theory, we calculated the thermal current autocorrelation functions from classical molecular dyn amics (MD) simulations. We examined the role of quantum corrections to the classical thermal conduction and concluded that these effects are small for fairly harmonic systems such as diamond. We then used the classical MD to extract thermal conductivities for bulk crystalline systems. We find that ( at 300 K) C-12 isotopically pure perfect diamond has a thermal conductivity 45% higher than natural (1.1% C-13) diamond. This agrees well with experim ent, which shows a 40%-50% increase. We find that vacancies dramatically de crease the thermal conductivity, and that it can be described by a reciproc al relation with a scaling as n(upsilon)(-alpha), with alpha =0.69 +/-0.11 in agreement with phenomenological theory (alpha =1/2 to 3/4). Such calcula tions of thermal conductivity may become important for describing nanoscale devices. As a first step in studying such systems, we examined the mass ef fects on the thermal conductivity of compound systems, finding that the lay ered system has a lower conductivity than the uniform system. (C) 2000 Amer ican Institute of Physics. [S0021-9606(00)70140-1].