UC Merced Chemist Wins DOE Award to Simulate Electron Motion at Quantum Speeds

Chemistry Professor Henrik Larsson has received a prestigious Early Career Award from the U.S. Department of Energy, becoming the first faculty member from UC Merced's School of Natural Sciences to earn the honor.

The award includes more than $878,000 in funding over five years to support Larsson's research into attochemistry - a field that explores how electrons move within molecules at speeds measured in attoseconds, or one-billionth of one-billionth of a second. An attosecond is to one second as one second is to the age of the universe, Larsson explained.

Larsson's work focuses on developing simulation tools to model electron behavior under extreme laser conditions. These simulations could help scientists better understand ultrafast phenomena such as charge migration and electron tunneling, which are critical to chemical reactions and the formation of new materials.

"Henrik's achievement is truly outstanding," said interim Dean Michael Findlater, a fellow chemistry professor. "This award recognizes the work he is pursuing in computational chemistry.

"It is fitting that as we celebrate our 20th year, achievements like this stand as a testament to our trajectory and the world-class science happening in the School of Natural Sciences."

The project builds on recent advances in laser technology that allow scientists to generate extremely short and intense light pulses across a range of wavelengths, from infrared to X-rays. These pulses make it possible to observe and potentially control the behavior of electrons and atomic nuclei in real time.

Larsson's lab will use quantum mechanics and advanced mathematical methods to simulate how electrons interact with each other and with atomic nuclei when exposed to these laser pulses. The goal is to understand how molecular structure and electron configuration influence ultrafast dynamics, and how atomic motion affects electron behavior.

The research will focus on molecules such as phenylalanine, an amino acid involved in protein synthesis and neurotransmitter production, as well as other aromatic compounds. By studying how electrons move through these molecules, Larsson hopes to uncover insights into the fundamental workings of matter.

Larsson's interest in ultrafast science began during his master's thesis in physics, and continued during his Ph.D. studies, when he explored femtochemistry - a field that operates on a slightly slower timescale than attochemistry and allows scientists to create "molecular movies" of chemical reactions.

"I was fascinated by how molecules involve not only atomic motion but also electron motion," Larsson said. "This field is deeply rooted in quantum mechanics. Often, quantum mechanics is taught as if wave functions don't move, but in reality, they do. That movement is fundamental to chemical reactions."

Larsson's academic journey has included work on electron dynamics, nuclear motion and electronic structure. He completed a postdoctoral fellowship at Caltech, where he applied mathematical tools from condensed matter physics to study chemical bonding. Now, he is combining those tools to simulate electron motion in attochemistry.

"What mainly drives me is understanding how I can even simulate this," he said. "Simulating the dynamics of attochemistry is incredibly difficult because electrons move so rapidly and interact on a quantum scale. Then, you have the nuclei coming in and also moving. That's really challenging."

Larsson said the goal is to use these simulations to reproduce experimental results and potentially discover new physical effects. His work is entirely theoretical, but he plans to collaborate with experimentalists once his methods are developed.

"There are already many experiments that go in that direction," he said. "They're able to create a movie of the electrons and their movement. For example, we're examining charge migration, where we remove an electron and observe how the vacancy - which acts like a positive charge - moves within a molecule."

Understanding how laser pulses and chemical modifications affect this movement could lead to new ways of controlling chemical reactions. Larsson said this might eventually allow scientists to break molecular bonds in specific locations and form new molecules that were previously impossible to create.

"For now, my main priority is to understand what's happening," he said. "Based on that, we can generate more ideas."

The techniques Larsson uses draw from multiple scientific communities, including condensed matter physics and electronic structure theory. He said combining these approaches has been essential to advancing his research.

The DOE award builds on earlier work supported by an ACS Petroleum Research Doctoral New Investigator Grant, which helped generate preliminary data and strengthen the application. Larsson and his team are now working on a publication that analyzes electron motion using concepts familiar to chemists, such as orbitals. He is looking for a postdoctoral scholar to work on the DOE-funded project. He is also interested in mentoring undergraduate and high school students.

"There's a great deal of knowledge and innovation needed," he said. "To me, being a scientist is like exploring new land - like wandering into a jungle, choosing a path based on some educated guess, and always finding something interesting."