Research On The Regulation Of Heat Transport In Low-dimensional Systems Based On Molecular Dynamics Simulation

With the advance of nanofabrication technology to low dimensions,heat transport in low-dimensional systems is becoming a common concern of both basic and applied research.In particular,with the recent experimental breakthroughs in low-dimensional materials such as nanowires,nanotubes,and two-dimensional graphene,it is found important to investigate nano-scale heat transports in low-dimensional systems.Compared with heat transport in macroscopic systems,heat transport in low-dimensional systems exhibits a dependence on the system scale.For example,graphene has a high thermal conductivity,which depends on the system size.At present,the research on the thermal properties and heat transport of low-dimensional systems has become a very important field of condensed matter physics.The main work of this paper is to study the effective control of graphene's thermal conductivity through designing graphene defects using molecular dynamics simulations.The research mainly has two parts.1)The structural shapes of different defects were designed to study the regulation mechanism of the defect shape of graphene on the thermal conductivity of graphene.By simulating and comparing the defects of different structures,we found that the square defects caused a significant decrease in thermal conductivity.Further analysis shows that there are fewer carbon atoms in the dangling bond around the square structure defect.Because these dangling bonds have strong scattering of low-dimensional heat transport,the carbon atoms with more dangling bonds will scatter phonon strongly.2)We have investigated the effect of spatial correlation and distribution of the structural defects on thermal transport in graphene.It is found that the porosity size and the number of defect size have a significant effect on thermal transport in graphene.Under the condition of the same porosity,we find that the decrease trend of graphene thermal conductivity is the most in the fractal defect.By designing the correlation distribution of low-dimensional system defects and their associated spatial locations,it provides possible ways and methods for the regulation of thermal conductivity and the control of heat flow in low-dimensional systems.It also contributes to designing new low-dimensional thermoelectric materials and thermal functional materials.