Simulating thermal fluctuations in soft matter models.
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Date
2015
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Abstract
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].
Description
Doctor of Philosophy in Physics. University of KwaZulu-Natal, Pietermaritzburg 2015.
Keywords
Solids -- Fluctuations., Condensed matter., Molecular dynamics., Theses -- Physics.