Atomistic interactions of clusters on surfaces using molecular dynamics and hyper molecular dynamics
Carlos F. Sanz-Navarro
2134/6814
https://repository.lboro.ac.uk/articles/thesis/Atomistic_interactions_of_clusters_on_surfaces_using_molecular_dynamics_and_hyper_molecular_dynamics/9375755
The work presented in this thesis describes the results of Molecular Dynamics (MD)
simulations applied to the interaction of silver clusters with graphite surfaces and
some numerical and theoretical methods concerning the extension of MD simulations
to longer time scales (hyper-MD).
The first part of this thesis studies the implantation of clusters at normal incidence
onto a graphite surface in order to determine the scaling of the penetration depth (PD) against the impact energy. A comparison with experimental results is made with good agreement. The main physical observations of the impact process are described and analysed. It is shown that there is a threshold impact velocity above which the linear dependence on PD on impact energy changes to a linear dependence on velocity. Implantation of silver clusters at oblique incidence is also considered.
The second part of this work analyses the validity and feasibility of the three
minimisation methods for the hyper-MD simulation method whereby time scales of
an MD simulation can be extended. A correct mathematical basis for the iterative
method is derived. It is found that one of the iterative methods, upon which hyper-
NID is based, is very likely to fail in high-dimensional situations because it requires
a too expensive convergence. Two new approximations to the hyper-MD approach
are proposed, which reduce the computational effort considerably. Both approaches,
although not exact, can help to search for some of the most likely transitions in the
system. Some examples are given to illustrate this.
2010-10-22 14:56:26
Atomic physics
Molecular physics
Solid state
Atoms
Molecules