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Speciale, 3. modul, 2013, id:291
Vejleder:Jeppe C. Dyre
Findes på RUb:Ja
English abstract
The aim of this Master's thesis is to analyse a classical and simple model of a liquid. The analysis consists of two parts: a theoretical analysis based on the isomorph theory and computer simulations. The computer simulations is done in the RUMD software. RUMD is a program used to perform Molecular Dynamics. The analyzed model consists of particles with pairwise interactions. The interactions are governed by a pair potential which decrease exponentially with distance. The interest in the model stems from the fact that though neglecting quantum mechanical effects, the model is aligned with quantum mechanics in the sense that the force between the particles mimic the probability distribution of electrons in simple atoms. The main results consists of a (formel) phase diagram of the liquid including the two main isomorph theoretically variables: R and (formel). An area with crystallisation and a phase transition between fluid and crystal are identified. No phase transition from liquid to gas is found, but the model exhibits gas-like structure in regions of the phase diagram. Application of isomorph theory leads to an analytic expression of isomorph lines dependent on one free parameter, in the phase diagram. Different methods for choosing this parameter is tested by generating isomorphs from two state points: One in the liquid part of the phase diagram and one on the coexistent line which is found to be an isomorph line. Another method of making isomorph lines is tested and rejected. The method is based on an observed linear correlation between coordinates of isomorphic phase points in an area of the phase diagram.

Database opslag den: 22-09-2017