We investigate the equilibrium properties and the relaxational dynamics of random heteropolymers in three dimensions. We proceed by studying an isolated random heteropolymer without an explicit solvent before studying different types of random heteropolymers in a monomeric solvent. Both equilibrium and relaxational data were obtained by performing extensive off-lattice molecular dynamics simulations. An equilibrium "phase diagram" is determined in all cases which facilitates the determination of a characteristic temperature separating extended states from collapsed states of the heteropolymer. This temperature is an increasing function of the strength of the random interactions and of the solvent density. It allows us to determine the appropriate initial and final temperatures to be used for the quenches from an extended coil to a collapsed globule. In particular for long isolated chains the heteropolymer collapse is a process which involves two distinct time regimes; both are energetically of stretched exponential form. Our simulation clearly shows the nature of the relaxation process where the formation of locally collapsed clusters takes place first followed by a global aggregation of the local blobs leading to the two collapse time regimes. Finally, we determine the effect of an explicit solvent on the collapse dynamics of a random heteropolymer. We bridge the difference between implicit and explicit solvents in two steps. First, we consider a heteropolymer with random interaction between the monomers, immersed in a purely repulsive solvent and we find that the rate of collapse increases with the strength of the random interaction but remains almost independent of the solvent density for higher values of the strength of the random interaction. Secondly, we look at a random heteropolymer with random interaction between the monomers and the solvent particles and we find that the rate of collapse increases slightly with density but is almost constant at low dens
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.38430 |
| Date | January 2001 |
| Creators | Villeneuve, Christine. |
| Contributors | Zuckermann, Martin (advisor), Guo, Hong (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001872834, proquestno: NQ78791, Theses scanned by UMI/ProQuest. |
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