Ellen Gulian

Major: Physics and Mathematics
Minor: Computer Science


Title: Studying 2D Transition Metal Dichalcogenides using Density Functional Theory.

Describe your project:2D transition metal dichalcogenides (TMDs) are a class of materials whose electronic and optical properties make them promising materials for devices like optical detectors and solar cells, and they can even have potential applications in quantum computing. In my project, I aim to use density functional theory, a quantum-mechanical computational tool, to study how these materials interact with their environment. Since these are 2D materials, they are exposed to their environment on all sides, and understanding the effects of this interaction can be vital when it comes to determining how we can use these materials in various devices. In particular, I will be using the Vienna Ab-initio Software Package (VASP) to investigate how introducing defects to monolayer TMDs, modifying the dielectric environment of the TMD, and placing various molecules on top of the monolayer changes the properties of the system.

Who is your mentor for your project?
Dr. Michael Hayden, Department of Physics. During my first semester at UMBC, Dr. Hayden invited me to attend his lab meetings, and I found that I was very interested in the research that his group was working on. I also found Dr. Hayden to be very friendly and outgoing, and I enjoyed the culture of his lab group a lot. I joined Dr. Hayden’s research group during my second semester at UMBC.

How did you become interested in this project?
When I first started in Dr. Hayden’s lab, my work was primarily experimental. I learned how to prepare thin-film samples of electro-optic polymers, make non-linear optical measurements, and also contributed to a joint research effort with the Army Research Lab that involved developing a sensor to detect defects in armor coating. Though I learned much through these projects, my interests and skills in physics evolved over time, and at the end of my sophomore year, I realized that what I wanted most was to work on a more theoretical research project that allowed me to synthesize my skills in physics, mathematics, and computer science. Dr. Hayden, in collaboration with Dr. Can Ataca’s research group, was able to come up with a project for me that was computational in nature but still relevant to the objectives of his lab group, and I started working on that project in my junior year.

What has been the hardest part about your research/what was the most unexpected thing about being a researcher?
One of the hardest parts of my research, and I think research in general, is developing intuition. In my research, sometimes a calculation will crash or terminate with some error code, and you need to be able to figure out what went wrong and determine how to fix the problem. In addition, depending on what type of calculation you want to do and what level of theory you are trying to use, you need to know the proper parameters to input to the computer, and when you’re examining the results of your calculations, you need to be able to determine when something looks “off” or when something cannot be physically correct. All of this requires some level of intuition regarding the physics of the problem you are considering, as well as a good understanding of how the software works.

I think the most unexpected thing about being a researcher, and perhaps something that’s a little uncomfortable at first, is that you can’t be completely prepared for your projects. From my work with Dr. Hayden and my work at various summer REU programs, I’ve learned that doing research means you pick up concepts as you go; it’s simply not realistic to think that you can learn all the prerequisites before starting a project. You’ll always encounter something that you haven’t seen before, and you need to learn how to deal with that in an efficient and effective way.

What has been the most rewarding part?
A lot of the time, computational work can feel like a black box – you use the tools and the software, but you don’t completely understand why or how it works. Personally, I’ve found that a strong understanding of the tools and methods used in a project gives me a greater appreciation of the research. Thus, I spent much of my time learning the fundamentals of density functional theory by reading papers and learning about the software through documentation, which has been a very rewarding experience. In addition, my project this year allows me to collaborate with a graduate student in our lab (Jon Gustafson), who is currently observing possible effects of air reacting with sulfur vacancies in monolayer MoS2 (a TMD). Having computational results from my DFT calculations will help us better determine possible mechanisms for these reactions, and I think it’s exciting to see how theory and experiment complement one another.

How will you disseminate your research?
I will be presenting my research at URCAD this April, and will also be looking to present at specialized (virtual) conferences throughout the year. From our preliminary results, we are also expecting a journal publication in the upcoming months.

What is your advice to other students about getting involved in research?
Don’t be shy about reaching out to potential research mentors early, even if you’re a freshman. You don’t have to make any commitments right away – you can just go to their lab meetings and see what the group is like and whether you’re really interested in the work. Also, look into summer research programs that you can apply for at other universities.

What are your career goals?
I’m applying to graduate programs in physics this fall. My goal is to earn my Ph.D. in theoretical condensed matter physics, and I’m especially interested in quantum materials and superconductivity. After getting my Ph.D., I plan on becoming a professor at a research university, where I can teach courses and start my own research group!


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