MPhys final year project: "Molecular Dynamics Simulation of Dipole Interactions". |
For my Master of Physics (MPhys) course, I undertook a year long research project. The initial aim was to attempt a molecular dynamics simulation of a droplet of water. Although after careful consideration, it was decided that a more simple simulation of ideal dipoles would more suit the time available.
I learnt just as much about academic research in general doing this project as I did about the molecular dynamics technique. My report is 43 pages, and so far I haven't converted it to HTML. I may do in the future, but in the meantime you can view as a PDF file, just click on the link below.
By viewing the report you are agreeing to respect my intellectual copyright and that of the references I have made within the text. Feel free to refer my work, on the provision that you do make a full reference in your reference section. I also forbid, any use of my report for plagiarism: this report is here for reference, not to help students meet their deadlines!
Abstract |
| This model investigates the
rotation of a rigid body with the molecular dynamics (MD)
method. Two ideal dipoles are modeled, both having their centre of
mass (COM) fixed in space. One dipole is
permitted to rotate about its COM the other is non-moving. Such a
configuration leads to the moving dipole
rotating under the influence of a dipolar electric field.
The relative positions of the two dipoles are chosen such that the
moving dipole may only rotate in one
plane. This allows the use of a local Spherical Polar (SP) coordinate
system (for measuring orientation in space). The mass and length of the
dipoles were chosen to reflect atomic
magnitudes. The dipole length was set to 5
Angstroms and
monopole mass was 1.6•10 -26
Kg.
All monopoles are given the charge of ± 1
electron charge.
Using a time step of 7•10 -18 seconds and starting with zero kinetic energy, the simulation showed that the dipole was confined in a potential well of the dipolar field. This confinement caused an oscillatory rotation. The amplitude and period of the oscillation were due to the initial position of the two dipoles, which set the initial potential energy. Clearly, with zero kinetic energy, the initial potential energy is equivalent to the total system energy. The period of oscillation was found to be approximately 2 Pico-seconds for a system-energy of 0.77 eV (2 d.p.). The value of this period sets a limit on the time-step size for such models in the future. |
Click here to read the whole report. |