Power-law divergent heat conductivity in one-dimensional momentum-conserving nonlinear lattices
Department of Physics, Renmin University of China - Beijing 100872, PRC
Accepted: 9 February 2011
We numerically study heat conduction in a few one-dimensional Fermi-Pasta-Ulam (FPU)-type lattices by both nonequilibrium heat bath and equilibrium Green-Kubo algorithms. In those lattices, heat conductivity κ is known to diverge with length N as Nα. It is commonly expected that the running exponent α should monotonously decreases with N and a recent study has shown that α for the FPU-β lattice saturates to 1/3 as N∼104. However, our calculations clearly show that α changes its behaviour, increasing towards the asymptotic value 2/5 for yet larger N values. As for the purely quartic lattice, α = 2/5 is clearly observed in four orders of magnitude of N ranging from 102 to 106. This unexpected reversal phenomenon can be observed more clearly in a much shorter FPU-αβ lattice.
PACS: 44.10.+i – Heat conduction / 05.60.Cd – Classical transport / 05.70.Ln – Nonequilibrium and irreversible thermodynamics
© EPLA, 2011