@article{briggs_lu_bernholc_2024, title={Adaptive finite differencing in high accuracy electronic structure calculations}, volume={10}, ISSN={["2057-3960"]}, url={https://doi.org/10.1038/s41524-024-01203-y}, DOI={10.1038/s41524-024-01203-y}, abstractNote={AbstractA multi-order Adaptive Finite Differencing (AFD) method is developed for the kinetic energy operator in real-space, grid-based electronic structure codes. It uses atomic pseudo orbitals produced by the corresponding pseudopotential codes to optimize the standard finite difference (SFD) operators for improved precision. Results are presented for a variety of test systems and Bravais lattice types, including the well-known Δ test for 71 elements in the periodic table, the Mott insulator NiO, and borax decahydrate, which contains covalent, ionic, and hydrogen bonds. The tests show that an 8th-order AFD operator leads to the same average Δ value as that achieved by plane-wave codes and is typically far more accurate and has a much lower computational cost than a 12th-order SFD operator. The scalability of real-space electronic calculations is demonstrated for a 2016-atom NiO cell, for which the computational time decreases nearly linearly when scaled from 18 to 144 CPU-GPU nodes.}, number={1}, journal={NPJ COMPUTATIONAL MATERIALS}, author={Briggs, E. L. and Lu, Wenchang and Bernholc, J.}, year={2024}, month={Jan} }
 @article{zhu_rui_lu_briggs_bernholc_zhang_2024, title={High-temperature semicrystalline/amorphous polymer blends exhibiting enhanced dielectric constant with high breakdown strength}, volume={128}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2024.109898}, journal={NANO ENERGY}, author={Zhu, Wenyi and Rui, Guanchun and Lu, Wenchang and Briggs, E. L. and Bernholc, J. and Zhang, Q. M.}, year={2024}, month={Sep} }
 @article{lupke_pham_zhao_zhou_lu_briggs_bernholc_kolmer_teeter_ko_et al._2022, title={Local manifestations of thickness-dependent topology and edge states in the topological magnet MnBi2Te4}, volume={105}, ISSN={["2469-9969"]}, url={https://doi.org/10.1103/PhysRevB.105.035423}, DOI={10.1103/PhysRevB.105.035423}, abstractNote={The interplay of non-trivial band topology and magnetism gives rise to a series of exotic quantum phenomena, such as the emergent quantum anomalous Hall (QAH) effect and topological magnetoelectric effect. Many of these quantum phenomena have local manifestations when the global symmetry is broken. Here, we report local signatures of the thickness dependent topology in intrinsic magnetic topological insulator MnBi$_2$Te$_4$(MBT), using scanning tunneling microscopy and spectroscopy on molecular beam epitaxy grown MBT thin films. A thickness-dependent band gap with an oscillatory feature is revealed, which we reproduce with theoretical calculations. Our theoretical results indicate a topological quantum phase transition beyond a film thickness of one monolayer, with alternating QAH and axion insulating states for even and odd layers, respectively. At an even-odd layer step, a localized gapped electronic state is observed, in agreement with an axion insulator edge state that results from a phase transition across the step. The demonstration of thickness-dependent topological properties highlights the role of nanoscale control over novel quantum states, reinforcing the necessity of thin film technology in quantum information science applications.}, number={3}, journal={PHYSICAL REVIEW B}, author={Lupke, Felix and Pham, Anh D. and Zhao, Yi-Fan and Zhou, Ling-Jie and Lu, Wenchang and Briggs, Emil and Bernholc, Jerzy and Kolmer, Marek and Teeter, Jacob and Ko, Wonhee and et al.}, year={2022}, month={Jan} }