Computer simulation for the polymeric solutionand bursting in excitable cells

Abstract

[Part A] Molecular Dynamic Study of a Polymeric Solution (I) Chain-Length Effect Dynamic and equilibrium structures of a polymer chain immersed in solvent molecules have been investigated by a molecular dynamic method. The calculation employs the Lennard-Jones potential function to represent the interactions between tow solvent molecules (SS) as well as between two non-nearest neighbor constituent particle (monomer unit) of the polymer chain and a solvent molecule (CS) as well as between two non-nearest neighbor constituent particles of the polymer chain (CC), while the chemical bond for nearest neighbor constituent particles was chosen to follow a harmonic oscillator potential law. The correlation function for the SS, CS and CS pairs, the end-to-end distance square and the radius of gyration square were calculated by varying the chain length (=5,10,15,20). The computed end-to-end distance square and the radius of gyration square were found to be in a fairly good agreement with the corresponding results from the random-flight model. Unlike earlier works, the present simulation result shows that the autocorrelation function of the radius of gyration square decays slower than that of the end-to-end distance square. [Part B] Molecular Dynamic Study of a Polymeric Solution (II) Solvent Effect Molecular dynamic method has been applied to a single polymer chain immersed in a solvent. The interactions between the solvent-solvent (SS), chain-solvent(CS), and non-neighbor chain particles (CC) are given by the Lennard-Jones potential, and the interaction between two bonded particles is given by a harmonic potential. We changed the chain-solvent interaction parameter $ε_{CS}$ as 0.5, 1.0 and 2.0 times of the solvent-solvent interaction $ε_{SS}$. We calculated the pair correlation functions, end-to-end distance and radius of gyration with the varying $ε_{CS}$ parameters. The results showed that a phase separation occurs between the polymer and solvent in the 0.5 system ...