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Simulating thermal fluctuations in soft matter models.

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The research carried out in this work is in two parts: In the first part, we derive a configurational temperature Nosé-Hoover thermostat by reformulating the original Braga and Travis thermostat [J. Chem. Phys. 123 (134101), 2005] in phase space using a quasi- Hamiltonian approach introduced by Sergi and Ferrario [Phys. Rev. E 64 (056125), 2001]. We also present a reversible integrator based on the symmetric Trotter decomposition of propagator for harmonic potentials and for more complicated potentials, a harmonic approximation of the potential is performed locally resulting in a positiondependent harmonically approximated propagator for a general system. In the second part of our work, we present a phonostat methodology based on classical molecular dynamics and Wigner approach to quantum mechanics. We introduce quantum effects into our system by generating a thermal profile using different ’effective’ temperature for the modes and coupling each one of the modes to a thermal bath. We test our phonostat algorithm against the range of temperatures and densities explored by Mausbach and May [Fluid Phase Equil. 249 (17), 2006].


Doctor of Philosophy in Physics. University of KwaZulu-Natal, Pietermaritzburg 2015.


Solids -- Fluctuations., Condensed matter., Molecular dynamics., Theses -- Physics.