0341341b_Nijs

1. Clustering induced phase transitions in driven stick-slip driven stochastic flow Marcel den Nijs (University of Washington)DMR 0341341 The so-called asymmetric exclusion process (ASEP) is a simple model to study stochastic driven flow through narrow channels. Its stationary state is uniform, but is known to be highly unstable towards clustering with respect to, e.g., defects (slow bonds). In recent studies in this field, e.g., of processes involving two Species driven in opposite directions, the clusters are stationary. Those have been approximated successfully in terms of zero- range processes, that ignore the internal cluster structure. In our generalization of ASEP, a particle can hop only to the right over one single site (stick) or can skip forward all the way to the site directly behind the particle in front of it (slip). This gives rise to strong clustering. These clusters have a non-zero group velocity, and a non-trivial internal structure that, e.g., determines whether the cluster group velocity is positive or negative. This determines whether the phase transition into the empty road phase is first or second order. In the figure, the time axis is vertical down.

2. Clustering induced phase transitions in driven stick-slip driven stochastic flow Marcel den Nijs (University of Washington)DMR 0341341 This research project is only the latest example of my ongoing interactions with my former Korean graduate students and post docs, in particular Prof. Hyunggyu Park (KIAS), Prof. Jae-Dong Noh (University of Seoul); and Prof. Meesoon Ha (Kaist). The educational component of these collaborations is invaluable. Prof. Doochul Kim at SNU played a crucial early role in this. Most of the funding driving this endeavor originates from Korean sources, like the Brain Korea 2000 program, and to a much lesser extend from this NSF grant. “Dynamic instability transitions in 1D driven diffusive flow with non-local hopping”, Meesoon Ha, Hyunggyu Park, and Marcel den Nijs, Phys. Rev. E 75, 061131 (2007).