纳米单原子链的热传导

根据Hardy能流密度公式、Kubo热导率公式,推导了纳米单原子链的热传导系数公式,并进行了数值计算.研究结果表明,纳米原子链的热传导系数小于无限长原子链的热传导系数,并且纳米原子链的长度越短,则热传导系数越小.这些现象可以作如下解释:原子链可以看作是一维晶格,格波在到达原子链端点时会发生反射,而改变了格波的能量传播方向,使能流密度降低,从而使纳米原子链的热导率小于无限长原子链的热导率.并且原子链越短,格波在到达原子链端点的过程中衰减越小,从而使反射格波的能流密度越接近于入射格波的能流密度,使能流密度更为降低,从而使纳米原子链的热导率更小.

Thermal conductivity of a monatomic nanochain

Based on Hardy's formula for energy flux and Kubo's formula for thermal conductivity,the Kubo's formula for thermal conductivity of monatomic nanochain is derived,and the numerical calculations are carried out.The results show that a monatomic nanochain has a smaller thermal conductivity than the corresponding infinite atomic chain,and a shorter monatomic nanochain has a smaller thermal conductivity.These results can be explained as follows: A atomic nanochain can be regarded as a finite one-dimensional crystal lattice,a lattice vibrational wave in it must be reflected at the ends, and its transport direction will be changed,all these will reduce the energy flux,and make the thermal conductivity of a monatomic nanochain smaller than that of the corresponding infinite nomatomic chain.For a shorter nanochain,the attenuation of a lattice vibration wave before it reach at ends will be smaller,the intensity of reflected wave will be closer to that of the incident wave,the net energy flux will be smaller,and the shorter atomic chain will have a smaller thermal conductivity.