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Velocity-gauge Real-time Time-dependent Density Functional Tight-binding for Large-scale Condensed Matter Systems

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arXiv

arXiv 2023年

作者： Xu, Qiang Del Ben, Mauro Okyay, Mahmut Sait Choi, Min Ibrahim, Khaled Z. Wong, Bryan M. Materials Science & Engineering Program Department of Chemistry Department of Physics & Astronomy University of California-Riverside RiversideCA92521 United States Applied Mathematics & Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

We present a new velocity-gauge real-time, time-dependent density functional tight-binding (VG-rtTDDFTB) implementation in the open-source DFTB+ software package (https://***) for probing electronic excitations in large, condensed matter systems. Our VG-rtTDDFTB approach enables real-time electron dynamics simulations of large, periodic, condensed matter systems containing thousands of atoms with a favorable computational scaling as a function of system size. We provide computational details and benchmark calculations to demonstrate its accuracy and computational parallelizability on a variety of large material systems. As a representative example, we calculate laser-induced electron dynamics in a 512-atom amorphous silicon supercell to highlight the large periodic systems that can be examined with our implementation. Taken together, our VG-rtTDDFTB approach enables new electron dynamics simulations of complex systems that require large periodic supercells, such as crystal defects, complex surfaces, nanowires, and amorphous materials. Copyright © 2023, The Authors. All rights reserved.

关键词： Gages

The Shear Contribution to the Equation of State: A Universal Law for the Elastic Moduli of Solids

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SSRN 2023年

作者： Burns, Stephen J. Burns, Sean P. Materials Science Program Department of Mechanical Engineering University of Rochester RochesterNY14627-0132 United States Mesoscale and Microscale Meteorology Division National Center for Atmospheric Research 3090 Center Green Drive BoulderCO80301 United States

Cauchy’s stress tensor, in the most generalized form, is known to be in two parts: a pressure plus octahedral shear stresses. Shear stress thermodynamics in pressurized and sheared systems are used to describe the physical shear properties of materials. Pressure alone does not fully describe solids although pressure is the basis for most equations of state. The thermal expansion coefficients are the major differences between normal and shear thermal strains. Shear-strain thermal expansion coefficients are central to predicting a material’s shear properties. Shear thermodynamics through the entropy-stress components predicts shear moduli proportional to a power-law in the specific volume. The concept is applied to all elastic moduli in solids and structures. Extensive empirical evidence supports elastic moduli that depend only on specific volume. The evidence is very extensive and leads to a new, generalized, universal, elastic moduli concept;it only applies to materials that support shear stresses i.e., solids. A shear equation of state is explored in detail with use of empirical data. © 2023, The Authors. All rights reserved.

关键词： Elasticity

Self-Powered, Flexible, and Instantly Dynamic Multi-Color Electroluminescence Device with Bi-Emissive Layers for Optical Communication

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SSRN 2023年

作者： Sun, Junlu Liao, Juan Dong, Fuying Chang, Yu Chang, Shulong Mao, Xin Li, Na Li, Xi Wang, Yong Shang, Yuanyuan Wang, Bin Shan, Chong-Xin Dong, Lin Henan Key Laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Materials Physics Ministry of Education School of Physics & Microelectronics Zhengzhou University 450052 China College of General Studies Shanxi Institute of Science and Technology 048000 China Department of Mechanical Engineering City University of Hong Kong China

Self-powered alternating current electroluminescence (ACEL) displays own distinctive preponderance in artificial electronic skins and information communication in the internet of things (IoT). However, their limited color options, i.e., monochrome or static multicolor, hinder their versatility. In this paper, we introduce an instantly dynamic multi-color display system that combines integrated bi-emissive layer ACEL with a dual-cells triboelectric nanogenerator (DC-TENG). Our bi-emissive ACEL device includes ZnS:Cu and ZnS:Mn phosphors blended in polydimethylsiloxane (PDMS) to achieve green and orange emissions, respectively. The DC-TENG consists of a polytetrafluoroetylene (PTFE) film and two copper tapes, generating an open-circuit voltage of ~270 V and a short-circuit current of ~2.5 μA, which is sufficient to power the bi-emissive layer ACEL device. By pressing the DC-TENG cell, the self-powered display system instantly renders green, orange and warm white emissions, making these dynamic multi-color responses useful as information units in the IoT. The self-powered optical communication system is demonstrated by transmitting the word "CHINA". Our study may provide a new approach for developing self-powered multi-color display systems and expands their potential applications in information communication for the IoT. © 2023, The Authors. All rights reserved.

关键词： Silicones

Effects of the unit-cell size and arrangement on the compressive behaviors of lattice structures in powder bed fusion additive manufacturing

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Results in Materials

Results in materials 2024年 22卷

作者： Park, Kwang-Min Roh, Young-Sook Lee, Bong-Chun Construction Technology Research Centre Construction Division Korea Conformity Laboratories Seoul 08503 South Korea Architectural Engineering Program Department of Architectural Engineering Seoul National University of Science and Technology Seoul 01811 South Korea Smart Construction Materials Centre Construction Division Korea Conformity Laboratories Chungbuk 28116 South Korea

Lattice structures demonstrate a unique compressive behavior wherein the compressive strength increases and converges to a specific value as the number of unit-cell arrangements and overall dimensions of the lattice structure increase. In this study, the effects of the unit-cell size and cell arrangement on the compressive behavior of lattice structures were investigated to determine the convergence of compression characteristics at specific unit-cell configurations. Simple cubic lattice structures were designed and manufactured using powder bed fusion techniques. The lattice structures were characterized using universal testing machines. Experimental results revealed that the convergence of compressive strength was influenced by the size of the unit cell: the number of arrangements at which a specific compressive strength was reached increased as the unit-cell sizes decreased. Furthermore, specific convergence points were determined for different unit-cell sizes, providing valuable insights into the compressive strength behavior of lattice structures. This study emphasizes the significance of considering both unit-cell arrangements and overall dimensions when designing standard specimens for compression testing. Additionally, the methodology developed in this study can be applied to obtain an optimal configuration for desired strength characteristics. © 2024 The Authors

关键词： Additive manufacturing Compressive behavior Lattice structure Powder bed fusion Unit-cell arrangement Unit-cell size

Lambda Theta Reflectometry for protein biosensing 17

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Lambda Theta Reflectometry for protein biosensing

Frontiers in Biological Detection: From Nanosensors to Systems XVII 2025

作者： Klose, Alanna M. Katz, Joseph D. Boni, Robert Miller, Benjamin L. Department of Dermatology University of Rochester RochesterNY14627 United States Materials Science Program University of Rochester RochesterNY14627 United States Laboratory of Laser Energetics University of Rochester RochesterNY14627 United States Department of Biomedical Engineering University of Rochester RochesterNY14627 United States

ISBN: (纸本)9781510684249

Label-free reflectometry sensors detect proteins by measuring the reflectance properties of a thin film on a substrate. As light encounters a thin film layer stack, reflections from the layer boundaries interfere with each other encoding information about layer properties onto the reflected light. Existing reflectometric techniques measure changes in thin film thickness by observing a change in the interference spectrum, polarization state or reflectance relative to an initial antireflective condition at fixed angle and wavelength. These techniques are used for biosensing by detecting changes in film thickness as analyte binds to surface-bound ligand. Existing approaches are limited by low multiplexing capability, limited sensitivity, or by requiring high manufacturing tolerances of the detector substrates. Lambda Theta Reflectometry (LTR) is a novel reflectometric technique that measures changes in film thickness by measuring the location of null reflectivity as a function of wavelength (lambda) and angle of incidence (theta). The substrate is simultaneously illuminated with a range of angles and wavelengths and reflected light is angularly and spectrally resolved. The optical thickness of the thin film is retrieved by fitting the location of the null in lambda theta space. A prototype LTR reflectometer has demonstrated the ability to measure SiO2 layer thickness with milli-Ångstrom precision. LTR measurements of SiO2/Si oxide films are in excellent agreement with spectroscopic ellipsometry for films thickness ranging from 1390-1465 Å. LTR enables sensitive measurements across a range of analyte concentrations without requiring stringent control over initial layer stack thickness. © 2025 SPIE.

关键词： Ellipsometry

Cyclic ferroelectric switching and quantized charge transport in CuInP2S6

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Physical Review B 2023年第18期108卷 L180101-L180101页

作者： Daniel Seleznev Sobhit Singh John Bonini Karin M. Rabe David Vanderbilt Department of Physics and Astronomy Center for Materials Theory Rutgers University Piscataway New Jersey 08854 USA Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New York New York 10010 USA

The van der Waals layered ferroelectric CuInP2S6 has been found to exhibit a variety of intriguing properties arising from the fact that the Cu ions are unusually mobile in this system. While the polarization switching mechanism is usually understood to arise from Cu ion motion within the monolayers, a second switching path involving Cu motion across the van der Waals gaps has been suggested. In this work, we perform zero-temperature first-principles calculations on such switching paths, focusing on two types that preserve the periodicity of the primitive unit cell: “cooperative” paths preserving the system's glide mirror symmetry, and “sequential” paths in which the two Cu ions in the unit cell move independently of each other. We find that CuInP2S6 features a rich and varied energy landscape, and that sequential paths are clearly favored energetically both for cross-gap and through-layer paths. Importantly, these segments can be assembled to comprise a globally insulating cycle with the out-of-plane polarization evolving by a quantum as the Cu ions shift to neighboring layers. In this sense, we argue that CuInP2S6 embodies the physics of a quantized adiabatic charge pump.

关键词： Electric polarization Electronic structure Ferroelectricity Phonons Structural phase transition

Field driven cluster formation in two-dimensional colloidal binary mixtures

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arXiv

arXiv 2022年

作者： Qian, Dingwen de la Cruz, Monica Olvera Applied Physics Program Northwestern University EvanstonIL60208 United States Applied Physics Program Departments of Materials Science and Engineering Chemistry and Physic and Astronomy Northwestern University EvanstonIL60208 United States

We study size- and charge-asymmetric oppositely charged colloids driven by an external electric field. The large particles are connected by harmonic springs, forming a hexagonal-lattice network while the small particles are free of bonds and exhibit fluid-like motion. We show that this model exhibits a cluster formation pattern when the external driving force exceeds a critical value. The clustering is accompanied with stable wavepackets in vibrational motions of the large particles. Copyright © 2022, The Authors. All rights reserved.

关键词： Binary mixtures

An Innovative Real-Time Cell Viability Analysis: A Cutting-Edge Flexible Bioimpedance Sensor

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SSRN 2023年

作者： Chou, Hsin-Yu Ching, Congo Tak-Shing Huang, Hui-Xuan Phan, Thien Luan Wang, Hui-Min David Department of Materials Science and Engineering National Chung Hsing University Taichung40227 Taiwan Ph.D. Program in Tissue Engineering and Regenerative Medicine National Chung Hsing University Taichung402 Taiwan Graduate Institute of Biomedical Engineering National Chung Hsing University Taichung40227 Taiwan Department of Electrical Engineering National Chi Nan University Nantou54561 Taiwan Department of Physic and Electronic Engineering Faculty of Physic and Engineering Physic Vietnam National University Ho Chi Minh City University of Science Viet Nam Graduate Institute of Medicine College of Medicine Kaohsiung Medical University Kaohsiung807 Taiwan Department of Medical Laboratory Science and Biotechnology China Medical University Taichung City404 Taiwan

There are many compounds to be used to treat cancer but still only 20% of proposed anticancer agents have been commercialized after clinical trials due to serious side effects and unsatisfactory results. To screen potential drugs precisely and quickly, this study develops a flexible bioimpedance sensor. The sensor is positive to detect the half maximal inhibitory concentration (IC50) of drugs real-time by analyzing phase angle changes during cell mortality. The best results are achieved using a probe separation of A12B34 at logarithmic frequencies of 163 Hz and 77.87 kHz. At these two frequencies, there is a linear relationship with the phase angle at 0% and 50% of the dead cells. Dividing the phase angle at the two frequencies shows a 17.98% change in the phase angle, which allows self-correction and insensitivity to the number of cells. A custom phase angle measurement device is developed for detection at 163 Hz and 77.87 kHz, respectively. This study develops a novel sensor that is precise, fast and allows high throughput analysis to detect the inhibition of cancer in real-time. This sensor is an alternative to traditional chemical detection methods because it is faster, cheaper and more accurate. © 2023, The Authors. All rights reserved.

关键词： Chemical detection

Low-Density Coalti-B2 Strengthened Al-Co-Cr-Mo-Ti Bcc Refractory High-Entropy Superalloy Designed with the Assistance of High-Throughput Calphad Method

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SSRN 2023年

作者： Yen, Shao-Yu Hideyuki, Murakami Lin, Shih-Kang Department of Materials Science and Engineering National Cheng Kung University Tainan70101 Taiwan School of Advanced Science and Engineering Research Center National Cheng Kung University Tainan70101 Taiwan Program on Smart and Sustainable Manufacturing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan70101 Taiwan Core Facility Center National Cheng Kung University Tainan70101 Taiwan

Superalloys are widely used in the power plants and turbine engines due to the superior mechanical performance at elevated temperatures and oxidation resistance in crucial environments. To enhance the currently commercial Ni-based superalloys, refractory elements are desired candidates for novel alloy development due to their ultrahigh melting points. In the past decade, refractory high-entropy superalloys (RSAs), which are the multi-principal refractory element-based alloys with the microstructure of ordered body-centered cubic (bcc) (B2) precipitates coherently embedded in the disordered bcc (A2) matrix, have attracted great attentions. However, most reported RSAs show the reversed microstructure of the continuous B2 phase with the discrete A2 phase forming via the spinodal decomposition, which have poor thermal stability at elevated temperatures. Herein we designed a coherent precipitate-strengthened Al-Co-Cr-Mo-Ti RSA with the assistance of high-throughput CALPHAD (HT-CALPHAD) calculation. Pandat software with PanHEA 2021 database were used in searching desired compositions. The alloy was fabricated by vacuum arc melting (VAM) and characterized with X-ray fluorescence spectroscopy (XRF), differential thermal analysis (DTA), X-ray diffractometry (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The desired microstructure of CoAlTi-B2 homogeneously dispersed in the A2 matrix was obtained, resulting in the high hardness. The coherent bcc/B2 RSA with high hardness-to-density ratio is developed. © 2023, The Authors. All rights reserved.

关键词： Microstructure