Role of pinning potentials in heat transport through disordered harmonic chain

The role of quadratic onsite pinning potentials on determining the size (N) dependence of the disorder averaged steady state heat current <J>, in a isotopically disordered harmonic chain connected to stochastic heat baths, is investigated. For two models of heat baths, namely white noise baths and Rubin's model of baths, we find that the N dependence of <J> is the same and depends on the number of pinning centers present in the chain. In the absence of pinning, <J> ~ 1/N^{1/2} while in presence of one or two pins <J> ~ 1/N^{3/2}. For a finite (n) number of pinning centers with 2 <= n << N, we provide heuristic arguments and numerical evidence to show that <J> ~ 1/N^{n-1/2}. We discuss the relevance of our results in the context of recent experiments.