Mean free path

About: Mean free path is a research topic. Over the lifetime, 4412 publications have been published within this topic receiving 114418 citations.

Anomalous heat conduction behavior in thin finite-size silicon nanowires

Abstract: Anomalous heat conduction behavior is observed for the first time using non-equilibrium molecular dynamics (NEMD) simulations to obtain the thermal conductivity of thin finite-size silicon nanowires (NWs) in the 001 lattice direction. In the series of simulations, the length dependence of thermal conductivity of thin silicon nanowires (NWs) ranging from 6 to 434 nm is analyzed. It is found that a transition occurs in the thermal conductivity versus length curve after the initial convergence trend appears near the mean free path of bulk silicon. Because no experimental measurements of thermal conductivity are available for sub-10 nm diameter silicon NWs, different NEMD methods are used to test and analyze this anomalous thermal behavior of thin Si NWs with different boundary conditions. The underlying mechanism of the observed behavior is inferred from MD simulations with different boundary conditions so that the anomalous behavior is mainly caused by border restriction and boundary scattering of the thin silicon NWs.

Use of generalized orthogonal polynomial solutions of Boltzmann’s equation in certain aeronomy problems: Auroral ion velocity distributions

Abstract: We present a method of solution of Boltzmann's equation that is valid for conditions where the species velocity distribution function departs significantly from a Maxwellian. This method should be particularly useful for problems in aeronomy and space physics where there are large or rapidly varying forces acting on a neutral or ionized gas or for problems dealing with highly rarefied gases where the mean free path for collisions is comparable to or greater than the characteristic scale length of the problem. The method of solution, which was first introduced by Mintzer, corresponds to expanding the species distribution function in a generalized orthogonal polynomial series with an arbitrary weight factor. The specific form of the weight factor depends on the details of the problem. The method is illustrated by calculating auroral ion velocity distributions for a relaxation collision model, and the results are compared with the velocity distributions obtained from an exact solution to Boltzmann's equation.

Metal-insulator transition of disordered interacting electrons

Abstract: We calculate the corrections to the conductivity and compressibility of a disordered metal when the mean free path is smaller than the screening length. Such a condition is shown to be realized for low densities and large disorder. Analysis of the stability of the metallic state reveals a transition to the insulating state in two dimensions.