- Title
- Advancing continuum modelling of intermolecular interactions with the Lennard-Jones Potential
- Creator
- Stevens, Kyle
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2023
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Nanomaterials have been a highly studied area for the past few decades, with their properties being explored in crucial applications such as gas storage and pollution capture. Both experimental and theoretical research into nanomaterials is thriving, however the theoretical models are primarily numerical simulations, with analytical methods making up a much smaller, yet still impactful, portion of publications. One of the more popular analytical methods is the continuum Lennard-Jones potential, which models the potential energy between molecules that can be approximated as surfaces or volumes. The continuum Lennard-Jones potential is used to great effect when the molecules considered are mono-nuclear with a homogeneous density,but falls short when modelling more heterogeneous molecules. This thesis aims to further the development of continuum Lennard-Jones potential modelling to better handle heterogeneous molecules. First, the current semi-continuous modelling techniques proposed for heterogeneous molecules are explored. This modelling technique involves partitioning the molecule into several homogeneous structures and treating their collection as a rigid body for the purposes of simplifying configuration. To investigate the effectiveness and scalability of this technique, a system of stacked coronene encapsulated within a carbon nanotube is modelled where the coronene is approximated by four concentric rings. The following chapters then concern the development of fully continuous approximations of molecules and how that affects the Lennard-Jones potential. To account for atomic species heterogeneity, interaction functions that replace the attractive and repulsive constants of the Lennard-Jones potential are introduced and used in modelling interactions involving coronene and methane with various carbon nanomaterials. Then, to account for atomic distribution heterogeneity, the atomic density coefficient is considered as a function and employed in a coronene-graphene interaction model. The results for all the models considered are found to be in better agreement with simulation results compared to the corresponding published semi-continuous models for most configurations. Lastly the thesis explores a method for using interaction functions for highly heterogeneous molecules by modelling a single-stranded DNA molecule interacting with graphene. Different approaches of partitioning the DNA molecule into segments of homogeneous patches that align with the monomers comprising DNA are considered, namely vertical and horizontal strips over which interaction functions are defined. The results from the model are compared with numerical results and a homogeneous model of DNA, and the lack of agreement both models have with simulation is analysed. Lastly, improvements to the DNA approximation are considered including replacing the single cosine interaction function with a sum of cosine and sine functions, and considering a helical cylinder rather than a helical ribbon. Overall the thesis presents a step forward in the development of continuum modelling of intermolecular interactions. The new techniques introduced to account for heterogeneous molecules show great agreement with simulations when the molecules are relatively simple, and promising future developments for more complicated molecules, leaving the door open for much more research.
- Subject
- continuum modelling; molecular interactions; carbon materials; nanomaterials
- Identifier
- http://hdl.handle.net/1959.13/1504313
- Identifier
- uon:55493
- Rights
- Copyright 2023 Kyle Stevens
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 17 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 192 KB | Adobe Acrobat PDF | View Details Download |