Diploma thesis

The title of my diploma thesis is "Coil-to-crystal transition of a polymer chain with square-well interactions: A transition path sampling simulation study".


We investigate the crystallization of a single, flexible homopolymer chain using transition path sampling (TPS). The chain consists of N identical spherical monomers evolving according to Metropolis Monte Carlo dynamics. While neighboring monomers have a fixed distance, the non-neighboring monomers interact via a square-well potential. For a sufficiently small interaction range λ, the system undergoes a first-order freezing transition from an expanded, unordered phase to a compact crystalline state. TPS and committor analysis are used to study the transition state ensemble of the chain and to search for possible reaction coordinates. Earlier observations concerning the structural properties of the transition states are confirmed by our calculations: The typical transition states indeed consist of a crystalline nucleus attached to one or more chain fragments. Furthermore, we investigate the statistical properties of TPS simulations and introduce the path survival function c(k). This quantity gives the average unchanged fraction of a transition path after k TPS iterations.


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