Thesis (MSc)--Stellenbosch University, 2004 / ENGLISH ABSTRACT: In an ongoing study an empirical force field that can correctly model N,N'-
dialkylimidazolium halide ionic liquids, the Imidazolium Ionic Liquid Force Field - IILFF,
was developed based on experimental data obtained from the Cambridge Structural Database
(CSD) and data calculated using Gaussian98.
Different conformations of the isolated cations were optimised at the Hartree-Fock
level using the 6-31G(d) basis set. Structural, vibrational and partial atomic charge data of the
lowest energy conformation of each cation were taken as observables during optimisation of
the force field parameters. Initial parameters of the IILFF were taken from existing force
fields and were optimised using the above mentioned data.
The IILFF was used to minimise isolated cations as well as crystals. These results were
successfully tested against isolated cations minimised using Gaussian98 and the experimental
crystals.
Finally, the melting process of the 1,3-dimethylimidazolium chloride crystal was studied
using an NPT ensemble starting from an ordered crystal cell and increasing the simulation
temperature beyond the experimental melting temperature. The IILFF was then used to
calculate the potential energy of the system. / AFRIKAANSE OPSOMMING: In 'n voortgaande studie om 'n empiriese kragveld te bou wat N,N' -dialkielimidasoliumhalied
ioniese vloeistowwe korrek kan modelleer is die Imidasolium Ioniese Vloeistof Kragveld
(nVK) ontwikkel. Die kragveld is ontwikkel gebasseer op eksperimentele data verkry uit die
Cambridge Strukturele Databasis (CSD) asook uit data vanaf Gaussian98 berekeninge.
Verskillende konformasies van die geïsoleerde katione is geoptimiseer deur middel van
Hartree Fock 6-31G(d) berekeninge. Strukturele data, asook vibrasies en gedeeltelike atoom
ladings van die laagste energie konformasie van elke katioon is gebruik as waarneembare
veranderlikes vir die bepaling van die optimale kragveld parameters. Beginwaardes vir die
nVK is geneem uit bestaande kragvelde en geoptimiseer met behulp van bogenoemde data.
Die IIVK is gebruik om geïsoleerde katione asook kristalle te minimiseer. Die resultate is
suksesvol getoets teen geïsoleerde katione wat met behulp van Gaussian98 geminimiseer is
en eksperimenteel bepaalde kristalle.
Laastens is die smeltproses van die 1,3-dimetielimidasolium chloried kristal bestudeer met
behulp van 'n NPT ensemble. Daar is begin by 'n geordende kristal en die simulasie
temperatuur is verhoog tot meer as die eksperimentele smeltpunt. Die IIVK is dan gebruik om
die potensiële energie van die sisteem te bepaal.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53737 |
| Date | 03 1900 |
| Creators | Musanur Abrar, Siraj |
| Contributors | Dillen, J. L. M., Esterhuysen, C, Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 123 pages : illustrations |
| Rights | Stellenbosch University |
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