Scientists Simulate Electron Localization in Real Materials

The insulator-to-metal transition in a monolayer hexagonal boron nitride. The transition requires both imperfections (δ) and electron-electron interactions (U). Image courtesy of NRL.

Scientists at the U.S. Naval Research Laboratory (NRL) (Washington, DC), in collaboration with Florida State University (Tallahassee, Florida), have developed a method to simulate electron localization in real materials, including imperfections and electron-electron interactions.

Electron localization is the tendency of electrons to become clustered in small regions of a material.

“In metals, the electronic states are delocalized, allowing electrons to move from site to site across the material,” says Daniel Gunlycke, head of NRL’s theoretical chemistry section. “Imperfections and electron-electron interactions, however, can localize the electronic states, turning a metal into an insulator. It provides us with a mechanism to control the electronic properties and engineer improved functionalities in existing as well as new materials for use in applications ranging from nanoscale optoelectronics to macroscale corrosion prevention.”

In their work, the authors present a new method by combining first-principles density functional theory, the Anderson-Hubbard model, and the medium dynamical cluster approximation within dynamical mean-field theory.

“There is a complex interplay between imperfections and electron-electron interactions in real materials,” says Chinedu Ekuma, a postdoctoral researcher in Gunlycke’s group. “Computer simulations enabled by our method are expected to reveal new critical insight.”

The new method to simulate electron localization in real materials has been applied to monolayer hexagonal boron nitride (h-BN), a large-gap insulator, and predicts that this is one material that requires both imperfections and electron-electron interactions to undergo an insulator-to-metal transition.

Source: NRL,