Dr. Xie Zhang receives High-Impact Scientific Computing – Early Career

NERSC Announces 2019 Early Career HPC Achievement Awards

January 13, 2020

Xie Zhang, University of California, Santa Barbara

Xie Zhang, a postdoctoral researcher in Chris Van de Walle’s group at the University of California, Santa Barbara, is being recognized in this category for producing essential insights into recombination mechanisms in hybrid perovskites – highly efficient materials for photovoltaics – based on cutting-edge first-principles simulations. Understanding the underlying mechanisms of these materials is essential for uncovering new design principles for efficient solar cell materials and for designing optimal device structures.

Toward this end, Zhang developed a first-principles approach to quantitatively compute the spin texture of the electron and hole bands and the radiative recombination coefficient. These calculations require complex computations of eigenvalues, wavefunctions, and dipole matrix elements for dense k-point meshes in the Brillouin zone. Benefiting from the computational resources provided by NERSC, Zhang demonstrated that the radiative recombination in hybrid perovskites is actually very strong – a finding that should put an end to misguided attempts to analyze and design device characteristics based on erroneous assumptions.

“Zhang has addressed technologically relevant problems in hybrid perovskites by combining cutting-edge quantum mechanical methodologies with the NERSC high-performance supercomputing facilities,” Van de Walle said. “The unique insights obtained in these studies provide a new understanding of these materials and point the way toward improving their performance.”

“I am thrilled to receive the prestigious NERSC Early Career Achievement Award. It is not only a distinct honor for myself, but also an affirmation of the fundamental and systematic approach to research in the Van de Walle group at UCSB,” Zhang said. “The constant support from my advisor and colleagues has been essential.”

Since joined the Van de Walle group in 2017, he added, “we have been focusing on elucidating the recombination mechanisms in halide perovskites and have built up a set of computational approaches to address this problem. The actual calculations require compute resources that are well beyond the capability of most supercomputing centers. NERSC made the realization of our highly demanding computations possible, allowing us to develop a deep understanding of how recombination in halide perovskites operates.”