Jennifer Brown, Author at Chemistry

Chemistry Professor Emeritus Michael J. Sepaniak Passes Away

April 8, 2024 by Jennifer Brown

It is with great sadness that we commemorate the passing of Michael J. Sepaniak, professor emeritus of chemistry. Sepaniak joined the Department of Chemistry at the University of Tennessee, Knoxville in 1981, where he spent nearly 40 years conducting research, teaching, and mentoring graduate students.

During his time at UT, Sepaniak investigated microfluidics, optical spectroscopy, and chemical sensing. He was a Paul and Wilma Ziegler Professor of Chemistry and served as department head from 1995 through 2003. Sepaniak retired in 2018, but maintained a post-retirement position with the department until 2020.

He will be greatly missed. The Department of Chemistry is grateful for his service and time at the university.

Rising Scholars: Dylan Andrews

December 6, 2023 by Jennifer Brown

Some students begin their college careers knowing they want a good education but unsure about what comes next, while others move in to their dorms with the next steps toward their career firmly in mind.

Dylan Andrews, senior honors chemistry major, was one of the latter. A native Tennessean, Andrews came to the University of Tennessee, Knoxville in pursuit of an education that would ultimately get him to medical school, starting with an undergraduate degree in chemistry.

“I was fortunate enough to have a really amazing chemistry instructor in high school, Mr. Mark Page. He was one of those teachers who truly makes an impact on you and he really helped me develop a love for chemistry,” said Andrews.

As he pursued his degree at UT, Andrews began to see participating in research as an opportunity to make the most of his time at the university and better prepare himself for the future. He broached the topic with Professor Janice Musfeldt, who was teaching one of his classes at the time.

“I think this is a really good example of how students can get involved in research in the department. Dr. Musfeldt and I built a good relationship over the course of the semester. I also met one of her graduate students and attended a seminar delivered by her colleague, Hans Bechtel. This let me get to know her group and her research, while showing her that I was engaged and interested,” said Andrews.

Hans Bechtel is the infrared program lead for the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. His ongoing relationship with the Musfeldt Group has led to him co-authoring several publications with its members. Bechtel visited the university to deliver a seminar and, over the course of conversation afterwards, suggested Andrews apply for a Department of Energy (DOE) summer internship at the Lawrence Berkeley Lab later in the year.

The next semester Andrews embraced research in the chemistry department as the next step toward his goals. He registered for the undergraduate research course and joined the Musfeldt lab. Heeding Bechtel’s advice, Andrews also applied for and was awarded a place in the DOE summer program at Lawrence Berkeley.

Near the end of spring semester, Andrews participated in the Department of Chemistry’s annual Undergraduate Research Symposium, presenting a poster to a panel of judges including departmental alumni, retired faculty, and industry partners. This experience gave Andrews his first chance to speak publicly about his research; an opportunity that would pave the way for future poster presentations.

At the end of his internship at Lawrence Berkeley Lab, Andrews entered and placed third in a poster competition designed to evaluate the presentation skills of the participants. The presentations were conducted via Zoom, allowing members of Andrews’ research team in the Musfeldt Group to join and support him.

Andrews plans to graduate in December 2024 and go on to medical school. He believes his experience in the Department of Chemistry and the relationships forged there have prepared him to meet the challenges of a future in medicine.

“Dr. Musfeldt, and really every faculty member I’ve worked with in the department, do everything they can to plug their students into new opportunities and point out things they could do to better themselves as students and researchers. I would probably never have known about that DOE internship if I hadn’t been introduced to Dr. Bechtel,” said Andrews. “The relationships I’ve developed and the support I’ve experienced in the chemistry department have really helped me excel as a student, which will help me through all the next stages of my education and career.”

Xue Group Publishes in Nature Communications

November 17, 2023 by Jennifer Brown

The Xue Research Group has published their recent work in the journal Nature Communications. The Xue Group is helmed by Professor Ziling (Ben) Xue, whose work includes materials chemistry and the study of magnetism.

Xue’s paper, “Haldane topological spin-1 chains in a planar metal-organic framework” describes his group’s work exploring the magnetic properties of NiBO. NiBO was previously reported as part of a family of two-dimensional metal coordination polymers, also known as MOFs (Metal-Organic Frameworks) but the possible topological magnetic properties of the material had not been investigated.

Xue’s team used a variety of techniques to examine the material, including variable-temperature powder neutron diffraction, inelastic neutron scattering, and Monte Carlo simulations of the spin-1 chains found in NiBO. They began testing not knowing what NiBO would reveal but the results of their work showed the material fell into a particular category of magnetic materials known as Haldane topological solids.

Haldane topological materials possess a specific magnetic characteristic that makes them potentially useful in spintronics (or spin electronics) and quantum computing. Xue’s findings could be relevant to the development of next-generation storage materials and the future of medical detectors.

Xue’s team included recent PhD graduate Pagnareach Tin and current PhD student Michael Jenkins, whose work he described as critical to the success of the project. The team also collaborated with Jie Xing and Rongyin Jin at the University of South Carolina, Nils Caci and Stefan Wessel at RWTH Aachen University in Germany, J. Krzystek at National High Magnetic Field Laboratory, and Zheng Gai, Cheng Li, Luke Daemen, and Yongqiang Cheng at Oak Ridge National Laboratory.

Read the full article here.

Vogiatzis Group Publishes in Journal of Physical Chemistry Letters

July 31, 2023 by Jennifer Brown

Grier Jones, fifth year chemistry PhD student, and Associate Professor Konstantinos Vogiatzis recently published a new data-driven quantum chemistry method, based on the reduced-density matrix (RDM) formulation of quantum mechanics, in the Journal of Physical Chemistry Letters. This publication was developed in collaboration with University of Tennessee, Knoxville alumnus Professor A. Eugene DePrince (’05) and his research group at Florida State University. DePrince’s group specializes in the development of novel RDM methods for the treatment of strongly correlated electrons.

Strong electron correlation lies at the heart of molecular quantum mechanics and, in particular, at the heart of electronic structure theory. Configuration interaction (CI) theory provides an exact description of strong correlation, but it suffers from exponential scaling with respect to the number of correlated electrons and orbitals. As an alternative, variational two-electron RDM (v2RDM) methods have been introduced since the energy of a many-electron system can be formulated exactly using the two-electron RDMs (2RDMs). One interesting property is that the 2RDM can be formulated without explicit knowledge of the wave function. In practice, finding a wave function that maps explicitly to the 2RDM can be very tricky, and the resulting deviation between CI- and RDM-based methods can be very large.

To resolve this issue, a collaboration between the Vogiatzis and DePrince groups lead to the development of the data-driven v2RDM (DDv2RDM) method to learn CI-quality energies using data generated using the v2RDM-complete active space self-consistent field (CASSCF) method. Using proof-of-principle calculations, they found that the model learns the correction the v2RDM energy near-chemical accuracy (1 kcal/mol). They also introduced the use of SHapley Additive exPlanation (SHAP) values, a feature importance method based on cooperative game theory, to analyze the how their physics-based features affect model performance. The SHAP analysis confirmed that the features that impact the model performance the most (and least) correspond well to insights based on physical principles.

Read the full article here.

Smith Breaks New Ground with Domain Wall Research

July 25, 2023 by Jennifer Brown

Kevin Smith, recent Ph.D. graduate from the department of chemistry, and Professor of Chemistry Janice Musfeldt have published the results of a collaborative investigation into the properties of ferroelectric domain walls. This research has generated a greater understanding of both a specific material, and domain walls in general, expanding the foundational knowledge critical to effectively using domain walls in future technologies.

Smith joined the chemistry department as a graduate student in 2015 and very quickly began investigating domain walls. Domain walls act as the boundaries between regions, or domains, of materials and have the potential to impact the properties and uses of that material.

Smith’s work specifically investigates the domain walls of ferroelectric materials, which have been a source of interest in the development of electronics. Efforts have been made to use domain walls as functional parts of devices as they could offer high speed memory reading and writing while requiring less energy to function.

Before ferroelectric domain walls can be successfully leveraged, researchers must develop a fundamental understanding of them and how they behave. It has long been hypothesized that these domain walls are atomically thin and conductive, but this had never been confirmed with a direct measurement at the wall. Smith and Musfeldt began investigating ferroelectric domain walls not with the intention of addressing this long-held belief, but with the goal of uncovering foundational information that could contribute to a greater understanding of these materials.

A collaboration with a group of physicists at Rutgers university, led by Henry Rutgers Professor Sang-Wook Cheong, provided Smith the material with which to begin his exploration.

“Our synthetic collaborators at Rutgers grew the material for us and provided some basic mapping on where to look for the domain walls,” said Smith. “We performed a line scan of the material with the near-field infrared microscope at Beamline 2.4 of the Advanced Light Source, or ALS, at Lawrence Berkeley National Lab. That’s when we started seeing these differences that we weren’t expecting to see.”

When thinking of a solid object, the expectation is often that the object is fairly uniform and that the components creating it are evenly distributed throughout that object. However, with the material Smith was investigating, the scan’s results were pointing toward different organizations of the material’s component parts in different regions of the material.

Smith and Musfeldt knew if they were going to uncover the source of these differences, they were going to need to investigate the material further, using the high-resolution infrared technique at the ALS to scan the material more thoroughly.

Beamline 2.4 of the ALS couples an atomic force microscope with synchrotron-generated infrared light to perform nanospectroscopy to examine materials on a much smaller scale than traditional microscopes. The microscope uses extremely sharply focused light delivered to an object at a very close distance. The response of the light as it interacts with the object is then collected and used to determine what is happening in that object.

“Using the ALS allowed us to examine these differences we were seeing in much greater detail. The material that we were studying was grown in such a way that it had two different types of metals in its A-site, scandium and lutetium. The ALS let us tease out three compositional arrangements for these materials that explained the differences. We found regions that were fairly evenly distributed, as well as both scandium-rich and lutetium-rich regions,” said Smith.

In addition to explaining the differences in domains with slightly different local composition, Smith and Musfeldt were able to determine the domain walls themselves were, in fact, much wider than traditionally believed. They also concluded that while they may have different conductivity than the surrounding regions, the domain walls were not metallic.

By successfully imaging ferroelectric domain walls, Smith and Musfeldt have accomplished something that has never been done before. As a result, they not only created a deeper understanding of these domain walls in a specific material, but also upended long-held beliefs about domain walls in general, paving the way for future innovation. Their work further highlights the importance of foundational and exploratory research in the development of future breakthroughs.

“This project really highlights the importance of curiosity in research,” said Musfeldt. “Kevin took an exploratory project and turned it into the most exciting thing in our lab with far-reaching implications.”

New materials are one potential path to improving existing technologies and generating new means of meeting the modern needs of people and society. Materials, however, are only useful insofar as they can be understood. Smith and Musfeldt’s work digs into the fundamental science behind a material’s properties, simultaneously creating a better understanding of that material and creating a roadmap for more effective uses for it in the future.

The full publication describing this research can be read here.

Vogiatzis named Bodossaki Distinguished Young Scientist

June 27, 2023 by Jennifer Brown

Konstantinos Vogiatzis, associate professor in the chemistry department, has been named a Bodossaki Distinguished Young Scientist Award winner. The award recognizes young Greek scientists for their work in a number of academic fields, including science, life sciences, applied science and technology, and the social sciences.

Vogiatzis’ work is centered on the development of computational methods based on electronic structure theory and artificial intelligence. He and his team apply this to chemical systems for clean, green technology.

“As an independent researcher, my work has focused on leveraging machine learning in computational chemistry, using modeling and simulation for the discovery of novel molecules and materials with enhanced properties,” said Vogiatzis. “The guiding objective of my research is to clarify the fundamental physical principles influencing the properties of molecules and materials through the interpretation of experimental data.”

Since 1993, the Bodossaki Foundation has distributed Distinguished Young Scientist Awards every two years. In that time, 57 Greek scientists have been recognized for outstanding research conducted across a global stage. Candidates for the Bodossaki Distinguished Young Scientist Award are nominated by peers, collaborators, and institutions in which they work. Vogiatzis was nominated by Vanda Glezakou, a colleague at Oak Ridge National Laboratory and fellow native of Greece.

Vogiatzis will attend a ceremony in Greece this summer where he will be presented with his award.As a Bodossaki honoree, Vogiatzis joins the ranks of Greek professors working at leading research institutions around the world, including Harvard University, the University of Oxford, and the University of Toronto.

“I would like to express my gratitude to the Bodossaki Foundation, both for recognizing my work and for the honor of being included among the outstanding scientists receiving these awards now and in years past,” said Vogiatzis. “This award is the result of a 17-year course of scientific study that began in the classrooms and research laboratories of Greek universities. This, however, is just the beginning and I look forward to many more years continuing the search for new discoveries in the field of chemistry.”

Vogiatzis joined the University of Tennessee, Knoxville in 2016. Since that time, he has authored more than 40 publications and mentored 15 graduate students. He is the recipient of the 2020 and 2022 Ffrancon Williams Endowed Faculty Award in Chemistry, the 2021 OpenEye Outstanding Junior Faculty Award presented by the American Chemical Society, and a 2021 NSF CAREER award.

Read more about the Bodossaki Foundation and the 2023 Distinguished Young Scientist awardees here.

Vogiatzis Group Publishes in npj Computational Materials

June 23, 2023 by Jennifer Brown

Associate Professor of Chemistry Konstantinos Vogiatzis, in collaboration with Professor of Mathematics Vasileios Maroulas and Eastman Chemical Company, has published a new machine learning model for predicting the properties of new polymeric materials.

Polymers are everywhere. From cookware to medical devices, polymers have become important to modern life due in part to a growing list of potential uses, and desirable properties like high durability and resistance to corrosion.

Creating new polymers can be an expensive, time-consuming process. Because of this, researchers attempt to predict the future properties of polymers using a variety of tools. Computational prediction methods allow researchers to screen polymer combinations for the desired properties before beginning experimentation. However, finding ways to represent polymers as machine-readable inputs can be difficult, creating a challenge for developing accurate prediction models.

Vogiatzis’ team is attempting to tackle these challenges by creating a deep learning method to predict polymer properties called PolymerGNN. PolymerGNN relies on state-of-the-art graph neural networks (GNN) and machine learning to predict the properties of new polymers using a database of complex polyesters.

“Polyesters offer a diverse material space formed by considering many different types of multifunctional acids and glycols, which are the building blocks of these materials,” said Vogiatzis. This, coupled with other complex properties of polyesters, creates a large materials design space Vogiatzis and his team were able to leverage in the development of PolymerGNN.

Vogiatzis worked with Vasileios Maroulas and students Owen Queen, Dr. Gavin McCarver and Sai Thatigotla to develop the general framework and GNN-based machine learning model for PolymerGNN. Collaborators from Eastman Chemical Company synthesized a set of more than 240 polymers and helped compile a database of properties which was used to train PolymerGNN.

Once trained, PolymerGNN accurately predicted both glass transition temperature and intrinsic viscosity. Glass transition temperature is the temperature at which a polymer shifts between a hard state and a softened state. Intrinsic viscosity is a measurement of a polymer’s molecular weight, which can indicate the polymer’s melting point, crystallinity, and tensile strength. These properties are fundamental to the ultimate physical traits of a given polymer and are critical to the development of adhesives, plastics, and more.

Vogiatzis’ team recently published this work in npj Computational Materials, an open access journal from Nature Research. They have also released PolymerGNN as an open-source codebase. Vogiatzis and Maroulas have collaborated on previous machine learning projects published by the American Chemical Society and Nature Communications. Read the most recent publication here.

Kevin Smith Featured by Berkeley Lab

April 26, 2023 by Jennifer Brown

Graduate student Kevin Smith and Professor Janice Musfeldt were recently featured by Lawrence Berkeley National Laboratory for their work with the Advanced Light Source (ALS). The highlight described the work in their paper entitled “Real-Space Infrared Spectroscopy of Ferroelectric Domain Walls in Multiferroic h-(Lu,Sc)FeO₃” published in ACS Applied Matter Interfaces.

Smith and Musfeldt used infrared light from the ALS to investigate the properties of the domain walls that separate electrically polarized regions in a rare-earth ferrite material. Their findings open the door to broadband imaging of physical and chemical heterogeneity in ferroics, and improved understandings of the properties of flexible defect states. The complete highlight is available here.

Chemistry Students Named Volunteers of Distinction

April 11, 2023 by Jennifer Brown

Two undergraduate chemistry students are included in the 2023 Volunteer of Distinction Award winners. Drake Robins and Clay West were nominated by faculty members and joined the ranks of students from across the university being honored.

Drake Robins is a fourth-year senior studying analytical chemistry. He is a member of the Air Force ROTC and has been working in Associate Professor Bhavya Sharma’s lab since his junior year. After graduation, Robins will join the United States Air Force and attend Undergraduate Pilot Training. Robins expressed his gratitude for the award and his time at the University of Tennessee.

“Academics and research have always been a top priority for me throughout my time at UT, and I feel extremely blessed to be recognized for it this close to graduation,” said Robins.

Clay West, also a fourth-year senior, is a student in the department’s American Chemical Society certified bachelor’s degree program. He plans to spend the year after graduation applying to graduate schools and preparing to pursue a PhD in organic chemistry. West stated he was grateful to receive the Volunteer of Distinction Award and considers it to be a reflection of the work he has put into earning his degree.

The Volunteer of Distinction Awards were created in 2021 by the university to recognize students across campus who exhibit extraordinary academic achievement, professional promise, or excellence in research. Previous award winners from the chemistry department include Maggie Eslinger, Hannah Hagewood, Elijah Hix, Galvin McCarver, and Wilson Wang.

Jones Wins NVIDIA GPU Poster Award

April 10, 2023 by Jennifer Brown

Grier Jones, fifth year chemistry PhD student, recently won a poster competition at the spring meeting of the American Chemical Society (ACS). His poster, entitled “Exploring the topology of electronic correlation with graph neural networks” earned the NVIDIA GPU Award for Best GPU Poster. The award targets excellent computational chemistry research using a graphical processing unit (GPU).

GPUs are most often associated with the high-quality images seen on gaming computers. However, the highly parallelized architecture of GPUs offers an acceleration platform that can outperform central processing units (CPUs) when processing large amounts of data in parallel. This has implications for scientific computing and machine learning applications, which have traditionally used CPUs.

Jones has developed a novel computational model that incorporates GPUs with graph neural networks (GNNs) and topological data analysis (TDA) to explore the topology of electron correlation. By incorporating two central motifs of the machine learning projects in the Vogiatzis lab, Data-Driven Quantum Chemistry (DDQC) and the application of persistent homology this study provides new perspectives on both the topological nature of electron correlation and the data-driven algorithms used to capture electron correlation.

For the purposes of this study, GPUs provided by the Infrastructure for Scientific Applications and Advanced Computing (ISAAC) cluster at the University of Tennessee were used. Training machine learning models on GPUs allows for the exploration of large datasets by reducing the computational time required to train the models. As a second step, persistent homology was used to characterize the transferability in the machine learning models between system size.

Jones expressed his gratitude to the Graduate Student Senate Travel Award and the Vogiatzis’ NSF-CAREER award for providing financial support for his participation in the ACS Spring 2023 National Meeting in Indianapolis. The award provides a professional workstation-level NVIDIA GPU, which Grier is excited to incorporate into his current and future projects.

The NVIDIA GPU Award for Best GPU Poster is a competitive biannual award sponsored by NVIDIA and the American Chemical Society’s Division of Computers in Chemistry.

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