Interpretation of apparent thermal conductivity in finite systems from equilibrium molecular dynamics simulations
journal contributionposted on 22.03.2021, 12:25 authored by Haikuan Dong, Shiyun Xiong, Zheyong Fan, Ping Qian, Yanjing Su, Tapio Ala-NissilaTapio Ala-Nissila
We propose a way to properly interpret the apparent thermal conductivity obtained for finite systems using equilibrium molecular dynamics simulations (EMD) with fixed or open boundary conditions in the transport direction. In such systems the heat current autocorrelation function develops negative values after a correlation time which is proportional to the length of the simulation cell in the transport direction. Accordingly, the running thermal conductivity develops a maximum value at the same correlation time and eventually decays to zero. By comparing EMD with nonequilibrium molecular dynamics (NEMD) simulations, we conclude that the maximum thermal conductivity from EMD in a system with domain length 2L is equal to the thermal conductivity from NEMD in a system with domain length L. This facilitates the use of nonperiodic-boundary EMD for thermal transport in finite samples in close correspondence to NEMD.
National Key Research and Development Program of China under Grants No. 2016YFB0700500 and No. 2018YFB0704300
National Natural Science Foundation of China under Grants No. 11974059 and No. 11804242
Science Foundation from Education Department of Liaoning Province under Grant No. LQ2020008
Academy of Finland through its QTF Centre of Excellence Programme under Project No. 312298
- Mathematical Sciences