Date of Award

2013-01-01

Degree Name

Doctor of Philosophy

Department

Computational Science

Advisor(s)

Tunna Baruah

Abstract

This project consists of performing upgrades to the massively parallel NRLMOL electronic structure code in order to enhance its performance by increasing its flexibility by: a) Utilizing dynamically allocated arrays, b) Executing in a parallel environment sections of the program that were previously executed in a serial mode, c) Exploring simultaneous concurrent executions of the program through the use of an already existing MPI environment; thus enabling the simulation of larger systems than it is currently capable of performing. Also developed was a graphical user interface that will allow less experienced users to start performing electronic structure calculations by aiding them in performing the necessary configuration of input files as well as providing graphical tools for the displaying and analysis of results. Additionally, a computational toolkit that can avail of large supercomputers and make use of various levels of approximation for atomic interactions was developed to search for stable atomic clusters and predict novel stable endohedral fullerenes.

As an application of the developed computational toolkit, a search was conducted for stable isomers of Sc3N@C80 fullerene. In this search, about 1.2 million isomers of C80 were optimized in various charged states at the PM6 level. Subsequently, using the selected optimized isomers of C80 in various charged state, about 10,000 isomers of Sc3N@C80 were constructed which were optimized using semi-empirical PM6 quantum chemical method. A few selected lowest isomers of Sc3N@C80 were optimized at the DFT level. The calculation confirms the lowest 3 isomers previously reported in literature but 4 new isomers are found within the lowest 10 isomers.

Using the upgraded NRLMOL code, a study was done of the electronic structure of a multichromoric molecular complex containing two of each borondipyrromethane dye, Zn-tetraphenyl-porphyrin, bisphenyl anthracene and a fullerene. A systematic examination of the effect of structural strain and the presence of ligands on the ionization energy and the electron affinity was also done. Finally, calculations were performed on a few lowest charge transfer states involving electronic transitions from the porphyrin component to the fullerene subunit of the complex using the perturbative delta-SCF method.

Language

en

Provenance

Received from ProQuest

File Size

87 pages

File Format

application/pdf

Rights Holder

Luis Basurto

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