纳米金刚石颗粒导热系数的分子动力学研究

Molecular dynamics study on thermal conductivity of diamond nanoparticles

应用分子动力学模拟的方法,研究了纳米金刚石颗粒的导热系数对温度和颗粒尺寸的依存关系.为了得到较为准确的模拟结果,采用了平衡态分子动力学模拟的方法.计算了较长时间的热流自相关函数,并得到了导热系数的收敛结果.结果表明,纳米金刚石颗粒由于尺寸的影响,导热系数低于体材料金刚石的导热系数;随温度的升高,导热系数出现一个峰值,该峰值点的温度小于体材料金刚石出现峰值点的温度;随颗粒尺寸的增大,导热系数增加,我们预测导热系数将在一定的颗粒尺寸时收敛于体材料金刚石的导热系数.

By using molecular dynamics （MD） simulation method, we studied temperature dependence and nanoparticle-size dependence of thermal conductivity of diamond nanoparticles. In order to get more reliable results, equilibrium molecular dynamics （EMD） method was applied. We set a relatively long integral time in the calculation of heat current autocorrelation function （HCACF）, and got convergent results. Our results indicate that due to size effect, thermal conductivity of diamond nanoparticles is smaller than the one of bulk diamond. As temperature varies, thermal conductivity shows a peak value at 61.6K, which behaves a little different from bulk diamond. As particle size increases, thermal conductivity increases; from the tendency of our plot, we predict that thermal conductivity of diamond nanoparticles will converge at the value of bulk diamond with a proper size. More work will be done on this prediction in our future researches.