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Position TitleComputational screening of organic dyes for photovoltaic applications
SummaryThe project investigates properties of a series of organic dyes, utilizing electronic structure methods. The intern will perform density functional theory calculations to determine the lowest energy conformations of the dyes, and calculate their ground and excited state properties, such as HOMO-LUMO gaps and UV-Vis absorption spectra. The intern will also develop software and protocols that will allow for calculations and subsequent analysis of properties in a large family of dyes (hundreds - thousands), thus utilizing the parallel capabilities of Blue Waters systems.
Job DescriptionThe intern’s primary task will be the calculation of structures and properties of organic dyes for eventual comparison of these calculated properties to experimental results. These dyes are obtained from NCSU’s Max A Weaver Dye Library, a vast collection of dyes with a wide variety of potential applications. Since the library contains some 90,000 samples, rapid screening and analysis of dyes via electronic structure methods is desirable to make the library and its compounds more easily accessible. Density functional theory (DFT) is the electronic structure calculation method of choice due to its more effective balance between efficiency and accuracy in comparison to other quantum chemical methods. However, various DFT methods need to be benchmarked against experimental data for different dye systems to understand the accuracy of the methods or shortcomings in the calculations. The intern will test five popular exchange-correlation functionals for this purpose: B3LYP, M06, CAM-B3LYP, ω-B97xD, and PBE, in each case using a triple-zeta Pople style basis set, 6-311G*. This selection offers a range of hybrid, pure, meta-hybrid and range-corrected functionals that have been used to study organic dyes in the past. This research will aid the community in selecting the most accurate DFT methodologies when computationally studying organic dye systems and will also provide useful information regarding specific families of dyes from the Max A Weaver Dye Library. The fundamental responsibilities of the intern will be performing geometry optimizations and conformational analysis to determine the optimal ground state structures, followed by time-dependent DFT (TD-DFT) to predict the dye’s electronic absorption spectra. The intern’s initial goal will be to analyze 200 specifically selected dyes, but the sample size can be expanded depending on how rapidly data is collected. Due to the large amount of data to be generated, it will not be feasible to analyze all of the results manually, so the intern will also implement custom software written in the Python language to automate post-processing of data for easy analysis and tabulation.
Use of Blue WatersThe intern will take advantage of petascale computing with the Blue Waters supercomputer in several different ways. Quantum chemistry software approximates solutions to quantum mechanical models for molecular systems of interest, and even in the simplest of systems this is a non-trivial problem. As these methods are complex, and we intend to study a great many dyes at different levels of theory, parallel computing employed by Blue Waters is absolutely essential to model systems of the molecular size and quantity that we require. Blue Waters already has implemented the well-established electronic structure program NWChem into its parallel architecture, so it will be simple to immediately take full advantage of available computing power by using NWChem to perform all of our required calculations. While running in serial would be far too inefficient, each individual dye molecule is only of modest size. It is expected that a typical dye will take at most three hours using 8 processors to successfully optimize, and no more than twelve hours using 8 processors to perform the TD-DFT on the XE6 standard compute nodes on Blue Waters.

Due to the volume of samples that we intend to utilize, the intern will be creating a program that can submit many calculations at one time. While this program need not initially be a parallelized program, it will take advantage of plentiful computing resources by submitting many independent calculations simultaneously. Data will be generated rapidly and then analyzed automatically through numerous simple and automated post-processing scripts written primarily in the Python language. Based on the massive number of organic dyes we intend to analyze, such analysis would constitute a large scale issue that will need extensive computing resources to address. Overall, the powerful parallel computing capabilities of Blue Waters would allow the intern to conduct a thorough and methodological investigation of the Max A. Weaver Dye library that could not be undertaken otherwise.
Conditions/Qualificationsundergraduate at NCSU, has taken at least one semester of Chemistry (CH 101 or CH 103)
Start Date05/30/2017
End Date05/29/2018
LocationChemistry Department, North Carolina State University, Raleigh, NC
Drew Marshburn