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Exploration of Electronic Structure and Optical Properties Hafnium (IV) Oxide and Its 12% Si, Ge and Sn with material Data Analysis by computational Methods 4th

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Exploration of Electronic Structure and Optical Properties H...

International Conference on 4th Industrial Revolution and Beyond, IC4IR 2021

作者： Chakma, Unesco Kumer, Ajoy Hossain, Tomal Sayed Hossain, Md. Monsur Alam, Md. Khandakar, Nusrat Jahan Shariful Islam, Md. Shaikh, Rubel Hazrat Ali, Md. Department of Electrical and Electronics Engineering European University of Bangladesh Gabtoli Dhaka1216 Bangladesh Laboratory of Computational Research for Drug Design and Material Science Department of Chemistry European University of Bangladesh Gabtoli Dhaka1216 Bangladesh Department of Chemistry Bangladesh University of Engineering Technology Dhaka1000 Bangladesh Center for Research Reactor Bangladesh Atomic Energy Commission Dhaka Bangladesh Department of Civil Engineering European University of Bangladesh Gabtoli Dhaka1216 Bangladesh European University of Bangladesh Gabtoli Dhaka1216 Bangladesh

ISBN: (纸本)9789811980312

This research work conveys the computational analysis of hafnium (IV) oxide and its doped crystal by Si, Ge and Sn replacing on the oxygen atom in HfO2, as hafnium (IV) oxide has been used in power-electronics devices of MOSFETs and electronics as RRAM due to wide band gap which makes a vast problems creating high resistances. Regarding this case, the hafnium (IV) oxide has selected inputs how the band gap has decreased later than doping by the large surface area atoms, such as Si, Ge and Sn. The first principle method in view of density functional theory (DFT) expresses the structural geometry, electronic structure and optical properties utilizing conformist calculations pertaining to HfO2 executing the computational avenue of the CASTAP regulation from material studio 8.0. The band gap was found in 4.340 eV, 2.033 eV, 1.686 eV and 3.210 eV for HfO2, Hf0.88Si0.12O2 Hf0.88Ge0.12O2 and Hf0.88Sn0.12O2 crystals through the Generalized Gradient Approximation (GGA) with Perdew Burke Ernzerhof (PBE), and the DFT and PDOS were simulated for evaluating the nature of 6s2, 5p6, 4f14, 5d2 orbital for a Hf atom, 3s2, 2p6 orbital for Si atom, 4s2,3p6, 3d10 orbital for Ge atom, 4d10, 5s2, 5p2 for Sn atom, 2s and 2p orbital for O atom of Hf0.88Ge0.12O2 and Hf0.88Sn0.12O2 crystals. The optical properties, for instance, absorption, reflection, refractive index, conductivity, dielectric function and loss function, were calculated. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Energy gap

Group Theory on Quasi-symmetry and Protected Near Degeneracy

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arXiv 2023年

作者： Li, Jiayu Zhang, Ao Liu, Yuntian Liu, Qihang Southern University of Science and Technology Shenzhen518055 China Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology Shenzhen518055 China

In solid state systems, group representation theory is powerful in characterizing the behavior of quasiparticles, notably the energy degeneracy. While conventional group theory is effective in answering yes-or-no questions related to symmetry breaking, its application to determining the magnitude of energy splitting resulting from symmetry lowering is limited. Here, we propose a theory on quasi-symmetry and near degeneracy, thereby expanding the applicability of group theory to address questions regarding large-or-small energy splitting. Defined within the degenerate subspace of an unperturbed Hamiltonian, quasi-symmetries form an enlarged symmetry group eliminating the first-order splitting. This framework ensures that the magnitude of splitting arises as a second-order effect of symmetry-lowering perturbations, such as external fields and spin-orbit coupling. We systematically tabulate the quasi-symmetry groups within 32 crystallographic point groups and demonstrate that Zn, U(1), and D∞ can serve as the quotient group of unitary quasi-symmetry group in doubly degenerate subspace. Applying our theory to the realistic material AgLa, we predict a "quasi-Dirac semimetal" phase characterized by two tiny-gap band anticrossings. © 2023, CC BY.

关键词： Spin orbit coupling

Ferroelectric switchable altermagnetism

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arXiv 2024年

作者： Gu, Mingqiang Liu, Yuntian Zhu, Haiyuan Yananose, Kunihiro Chen, Xiaobing Hu, Yongkang Stroppa, Alessandro Liu, Qihang Department of Physics Guangdong Basic Research Center of Excellence for Quantum Science Southern University of Science and Technology Shenzhen518055 China Korea Institute for Advanced Study Seoul02455 Korea Republic of Coppito Italy Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China

We propose a novel ferroelectric switchable altermagnetism effect, the reversal of ferroelectric polarization is coupled to the switching of altermagnetic spin splitting. We demonstrate the design principles for the ferroelectric altermagnets and the additional symmetry constraints necessary for switching the altermagnetic spin splitting through flipping the electric polarization based on the state-of-the-art spin-group symmetry techniques. 22 ferroelectric altermagnets are found by screening through the 2001 experimental reported magnetic structures in the MAGNDATA database and 2 of them are identified as ferroelectric switchable altermagnets. Using the hybrid improper ferroelectric material [C(NH2)3]Cr(HCOO)3 as an example, we show how the altermagnetic spin splitting is tightly coupled to the ferroelectric polarization, providing an ideal platform for designing electric-field-controllable multiferroic devices. Finally, we find that such manipulation of altermagnetism can be detected by monitoring the physical quantities that are related to the non-vanishing Berry curvature dipole, such as the linearly polarized photogalvanic spin current. © 2024, CC BY.

关键词： Ferroelectric materials

Catalog of Unconventional Magnons in Collinear Magnets

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arXiv 2023年

作者： Chen, Xiaobing Liu, Yuntian Liu, Pengfei Yu, Yutong Ren, Jun Li, Jiayu Zhang, Ao Liu, Qihang Department of Physics Guangdong Basic Research Center of Excellence for Quantum Science Southern University of Science and Technology Shenzhen518055 China Shenzhen518045 China Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China

Topological magnons have garnered significant interest for their potential in both fundamental research and device applications, owing to their exotic, uncharged, yet topologically protected boundary modes. However, their comprehension has been hindered by the absence of fundamental symmetry descriptions of magnetic materials, which are primarily governed by isotropic Heisenberg interactions in spin Hamiltonians. The ensuing magnon dispersions enable gapless magnon band nodes that go beyond the scenario of representation theory of the magnetic space groups (MSGs), thus referred to as unconventional magnons. Here we developed spin space group (SSG) theory to elucidate collinear magnetic configurations, classifying the 1421 collinear SSGs into four types, constructing their band representations, and providing a comprehensive tabulation of unconventional magnons, such as duodecuple points, octuple nodal lines, and charge-4 octuple points. Based on the MAGNDATA database, we identified 498 collinear magnets with unconventional magnons, among which over 200 magnon band structures were obtained by using first-principles calculations and linear spin wave theory. Additionally, we evaluated the influence of the spin-orbit coupling-induced exchange interaction in these magnets and found that more than 80% are predominantly governed by the Heisenberg interactions, indicating that SSG serves as an ideal framework for describing magnon band nodes in most 3d, 4d and half-filled 4f collinear magnets. Our work offers new pathways for exploring uncharged transports in magnonic systems, holding promise for advancements in next-generation spintronic devices. © 2023, CC BY.

关键词： Topology

Magnetic geometry to quantum geometry nonlinear transports

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arXiv 2024年

作者： Zhu, Haiyuan Li, Jiayu Chen, Xiaobing Yu, Yutong Liu, Qihang Department of Physics Guangdong Basic Research Center of Excellence for Quantum Science Southern University of Science and Technology Shenzhen518055 China New Cornerstone Science Laboratory Department of Physics The University of Hong Kong 999077 Hong Kong Shenzhen518045 China Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China

Nonlinear transports (NLTs) have garnered broad attention based on their topological origin in quantum geometry. When quantum geometry meets magnetic geometry in magnets, their crossover excites diverse phenomena particularly related to antiferromagnetic spintronics. However, very few material platforms have been predicted and experimentally verified to date, where the material pool was subconsciously narrowed down due to the demand for spin-orbit coupling (SOC). Therefore, to boost antiferromagnetic spintronics, we consider the magnetic order induced quantum geometry and corresponding NLTs in antiferromagnets (AFMs). By integrating the state-of-the-art spin space group theory into the symmetry analysis, we find that collinear and coplanar magnetic geometry can only induce NLT driven by Berry curvature dipole, and noncoplanar one may trigger NLT driven by dipoles of Berry curvature, inverse mass, and quantum metric. Remarkably, a materials database of 260 AFMs with SOC-free NLT effects is established. Several prototypical material candidates are presented by first-principles calculations, including collinear AFM VNb3S6 with NLT driven by Berry curvature dipole, and a room-temperature noncoplanar AFM CrSe with NLTs driven by quantum metric dipole. Our work not only provides a universal theoretical framework for studying various magnetism-driven transport effects, but also predicts broad, experimentally accessible material platforms for antiferromagnetic spintronics. © 2024, CC BY.

关键词： Nanocrystals

Real-time Impurity Solver Using Grassmann Time-Evolving Matrix Product Operators

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arXiv 2024年

作者： Chen, Ruofan Xu, Xiansong Guo, Chu College of Physics and Electronic Engineering Center for Computational Sciences Sichuan Normal University Chengdu610068 China Science and Math Cluster Singapore University of Technology and Design 8 Somapah Road 487372 Singapore Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control Ministry of Education Department of Physics Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha410081 China

An emergent and promising tensor-network-based impurity solver is to represent the Feynman-Vernon influence functional as a matrix product state, where the bath is integrated out analytically. Here we present an approach to calculate the equilibrium impurity spectral function based on the recently proposed Grassmann time-evolving matrix product operators method. The central idea is to perform a quench from a separable impurity-bath initial state as in the non-equilibrium scenario. The retarded Green's function G(t + t0, t′ + t0) is then calculated after an equilibration time t0 such that the impurity and bath are approximately in thermal equilibrium. There are two major advantages of this method. First, since we focus on real-time dynamics, we do not need to perform the numerically ill-posed analytic continuation as in the imaginary time evolution based methods. Second, the required bond dimension of the matrix product state in real-time calculations is observed to be much smaller than that in imaginary-time calculations, leading to a significant improvement in numerical efficiency. The accuracy of this method is demonstrated in the single-orbital Anderson impurity model and benchmarked against the continuous-time quantum Monte Carlo method. Copyright © 2024, The Authors. All rights reserved.

关键词： Monte Carlo methods

Grassmann Time-Evolving Matrix Product Operators: an Efficient Numerical Approach for Fermionic Path Integral Simulations

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arXiv 2024年

作者： Xu, Xiansong Guo, Chu Chen, Ruofan College of Physics and Electronic Engineering Center for Computational Sciences Sichuan Normal University Chengdu610068 China Science Math and Technology Cluster Singapore University of Technology and Design 8 Somapah Road Singapore487372 Singapore Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha410081 China

Developing numerical exact solvers for open quantum systems is a challenging task due to the non-perturbative and non-Markovian nature when coupling to structured environments. The Feynman-Vernon influence functional approach is a powerful analytical tool to study the dynamics of open quantum systems. Numerical treatments of the influence functional including the quasi-adiabatic propagator technique and the tensor-network-based time-evolving matrix product operator method, have proven to be efficient in studying open quantum systems with bosonic environments. However, the numerical implementation of the fermionic path integral suffers from the Grassmann algebra involved. In this work, we present a detailed introduction of the Grassmann time-evolving matrix product operator method for fermionic open quantum systems. In particular, we introduce the concepts of Grassmann tensor, signed matrix product operator, and Grassmann matrix product state to handle the Grassmann path integral. Using the single-orbital Anderson impurity model as an example, we review the numerical benchmarks for structured fermionic environments for real-time nonequilibrium dynamics, real-time and imaginary-time equilibration dynamics, and its application as an impurity solver. These benchmarks show that our method is a robust and promising numerical approach to study strong coupling physics and non-Markovian dynamics. It can also serve as an alternative impurity solver to study strongly-correlated quantum matter with dynamical mean-field theory. © 2024, CC BY.

关键词： Tensors

Emergence of steady currents due to strong prethermalization

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Physical Review A 2023年第2期107卷 022220-022220页

作者： Xiansong Xu Chu Guo Dario Poletti Science Mathematics and Technology Cluster Singapore University of Technology and Design 8 Somapah Road Singapore 487372 Singapore College of Physics and Electronic Engineering and Center for Computational Sciences Sichuan Normal University Chengdu 610068 China Henan Key Laboratory of Quantum Information and Cryptography Zhengzhou Henan 450000 China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China EPD Pillar Singapore University of Technology and Design 8 Somapah Road Singapore 487372 Singapore The Abdus Salam International Centre for Theoretical Physics Strada Costiera 11 34151 Trieste Italy Centre for Quantum Technologies National University of Singapore Singapore 117543 Singapore

A steady current between baths is a manifestation of the prethermalization phenomenon, a quasiequilibrium dynamic process with weak breaking of conserved quantities. We consider two finite nonintegrable many-body baths, each following the eigenstate thermalization hypothesis and each prepared in a random product state with fixed and different energy constraints, i.e., within the mean energy ensemble. Such an initialization, not being constrained to superpositions or mixtures of many-body eigenstates, opens the door to experimental realization and also significantly simplifies numerical simulations. We show that such a dynamic process is typical as the current variance decreases exponentially with respect to the size of baths. We also demonstrate that the emerging current is prethermalized in a strong sense, analogous to strong thermalization, meaning that the current values stay close to the microcanonical one most of the time.

关键词： Eigenstate thermalization Nonequilibrium statistical mechanics Open quantum systems & decoherence Nonequilibrium systems

DPA-2:a large atomic model as a multitask learner

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npj computational materials 2024年第1期10卷 185-199页

作者： Duo Zhang Xinzijian Liu Xiangyu Zhang Chengqian Zhang Chun Cai Hangrui Bi Yiming Du Xuejian Qin Anyang Peng Jiameng Huang Bowen Li Yifan Shan Jinzhe Zeng Yuzhi Zhang Siyuan Liu Yifan Li Junhan Chang Xinyan Wang Shuo Zhou Jianchuan Liu Xiaoshan Luo Zhenyu Wang Wanrun Jiang Jing Wu Yudi Yang Jiyuan Yang Manyi Yang Fu-Qiang Gong Linshuang Zhang Mengchao Shi Fu-Zhi Dai Darrin M.York Shi Liu Tong Zhu Zhicheng Zhong Jian Lv Jun Cheng Weile Jia Mohan Chen Guolin Ke Weinan E Linfeng Zhang Han Wang AI for Science Institute BeijingP.R.China DP Technology BeijingP.R.China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijingP.R.China State Key Lab of Processors Institute of Computing TechnologyChinese Academy of SciencesBeijingP.R.China University of Chinese Academy of Sciences BeijingP.R.China HEDPS CAPTCollege of EngineeringPeking UniversityBeijingP.R.China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingboP.R.China CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Chinese Academy of SciencesNingboP.R.China School of Electronics Engineering and Computer Science Peking UniversityBeijingP.R.China Shanghai Engineering Research Center of Molecular Therapeutics&New Drug Development School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghaiP.R.China Laboratory for Biomolecular Simulation Research Institute for Quantitative Biomedicine and Department of Chemistry and Chemical BiologyRutgers UniversityPiscatawayNJUSA Department of Chemistry Princeton UniversityPrincetonNJUSA College of Chemistry and Molecular Engineering Peking UniversityBeijingP.R.China Yuanpei College Peking UniversityBeijingP.R.China School of Electrical Engineering and Electronic Information Xihua UniversityChengduP.R.China State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchunP.R.China Key Laboratory of Material Simulation Methods&Software of Ministry of Education College of PhysicsJilin UniversityChangchunP.R.China International Center of Future Science Jilin UniversityChangchunP.R.China Key Laboratory for Quantum Materialsof Zhejiang Province Department of PhysicsSchool of ScienceWestlake UniversityHangzhouP.R.China Atomistic Simulations Italian Institute of TechnologyGenovaItaly State Key Laboratory of Physical Chemistry of Solid Surface iChEMCollege of Chemistry and Chemical EngineeringXiame

The rapid advancements in artificial intelligence(AI)are catalyzing transformative changes in atomic modeling,simulation,and ***-driven potential energy models havedemonstrated the capability to conduct large-scale,long-duration simulations with the accuracy of ab initio electronic structure ***,the model generation process remains a bottleneck for large-scale *** propose a shift towards a model-centric ecosystem,wherein a large atomic model(LAM),pretrained across multiple disciplines,can be efficiently fine-tuned and distilled for various downstream tasks,thereby establishing a new framework for molecular *** this study,we introduce the DPA-2 architecture as a prototype for ***-trained on a diverse array of chemical and materials systemsusing a multi-task approach,DPA-2demonstrates superior generalization capabilities across multiple downstream tasks compared to the traditional single-task pre-training and fine-tuning *** approach sets the stage for the development and broad application of LAMs in molecular and materials simulation research.

关键词： DPA establishing thereby