Molecular dynamics with quantum heat baths: Application to nanoribbons and nanotubes

Abstract

A generalized Langevin equation with quantum heat baths [quantum molecular dynamics (QMD)] for thermal transport is derived with the help of nonequilibrium Green's function (NEGF) formulation. The exact relationship of the quasiclassical approximation to NEGF is demonstrated using Feynman diagrams of the nonlinear self-energies. To leading order, the retarded self-energies agree but QMD and NEGF differ in lesser/greater self-energies. An implementation for general systems using Cholesky decomposition of the correlated noises is discussed. Some means of stabilizing the dynamics is given. Thermal conductance results for graphene strips and carbon nanotubes are presented. The "quantum correction" method is critically examined. © 2009 The American Physical Society.