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Anomalous Hall effect,magneto-optical properties,and nonlinear optical properties of twisted graphene systems

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npj Computational Materials 2020年第1期6卷 1172-1181页

作者： Jianpeng Liu xi dai Department of Physics Hong Kong University of Science and TechnologyKowloonHong KongChina

We study the anomalous Hall effect,magneto-optical properties,and nonlinear optical properties of twisted bilayer graphene aligned with hexagonal boron nitride substrate,as well as twisted double bilayer graphene *** show that non-vanishing valley polarizations in twisted graphene systems would give rise to the anomalous Hall effect,which can be tuned by in-plane magnetic *** valley polarized states are also associated with giant Faraday and Kerr rotations in the terahertz frequency ***,we propose that the twisted graphene systems exhibit colossal nonlinear optical responses by virtue of the inversion-symmetry breaking,the small bandwidth,and the small excitation gaps of the *** twisted double bilayer graphene,we find that certain components of the nonlinear photo-conductivity tensor are directly proportional to the orbital magnetization of the system,which would exhibit remarkable hysteresis behavior in response to perpendicular magnetic fields.

关键词： twisted nonlinear hexagonal

Evaluating genetic insights into ulcerative colitis and anxiety:Limitations and future directions

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World Journal of Gastroenterology 2024年第37期30卷 4156-4159页

作者： Ying Peng xi-dai Long Department of Pathology The First Affiliated HospitalGuangxi Medical UniversityNanning 530021Guangxi Zhuang Autonomous RegionChina Department of Pathology Shenzhen Qianhai Shekou Free Trade Zone HospitalShenzhen 518000Guangdong ProvinceChina Department of Pathology The Affiliated Hospital of Youjiang Medical University for NationalitiesBaise 533000Guangxi Zhuang Autonomous RegionChina Department of Liver Surgery Ren Ji HospitalSchool of MedicineShanghai Jiaotong UniversityShanghai 200000China

We reviewed the study by He et al,which investigates the genetic correlation between ulcerative colitis(UC)and anxiety using bidirectional Mendelian *** study reveals a genetic link between UC and anxiety,diverging from prior research associating higher anxiety with Crohn’s *** the study's use of large-scale genome-wide association studies data is commendable,it faces limitations such as single nucleotide polymorphism selection biases,lack of multiple testing corrections,and a reliance on European *** research should address these limitations,incorporate diverse populations,and explore psychotherapeutic interventions to improve UC management and patient outcomes.

关键词： Ulcerative colitis Anxiety Mendelian randomization Genome-wide association study Gut-brain axis Instrumental variables Genetic epidemiology Pleiotropy

Differentiable programming and density matrix based Hartree–Fock method

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Chinese Physics B 2021年第6期30卷 249-254页

作者： Hong-Bin Ren Lei Wang xi dai Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China Department of Physics Hong Kong University of Science and TechnologyClear Water BayKowloon 999077Hong KongChina

Differentiable programming is an emerging programming paradigm that allows people to take derivative of an output of arbitrary code snippet with respect to its input. It is the workhorse behind several well known deep learning frameworks,and has attracted significant attention in scientific machine learning community. In this paper, we introduce and implement a density matrix based Hartree–Fock method that naturally fits into the demands of this paradigm, and demonstrate it by performing fully variational ground state calculation on several representative chemical molecules.

关键词： differentiable programming quantum chemistry

Machine Learning Kinetic Energy Functional for a One-Dimensional Periodic System

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Chinese Physics Letters 2021年第5期38卷 1-6页

Kinetic energy(KE) functional is crucial to speed up density functional theory calculation. However, deriving it accurately through traditional physics reasoning is challenging. We develop a generally applicable KE functional estimator for a one-dimensional (1D) extended system using a machine learning method. Our end-to-end solution combines the dimensionality reduction method with the Gaussian process regression, and simple scaling method to adapt to various 1D lattices. In addition to reaching chemical accuracy in KE calculation, our estimator also performs well on KE functional derivative prediction. Integrating this machine learning KE functional into the current orbital free density functional theory scheme is able to provide us with expected ground state electron density.

关键词： red Gaussian DFT Machine Learning Kinetic Energy Functional for a One-Dimensional Periodic System

Topological nodal line semimetals predicted from first-principles calculations

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Frontiers of physics 2017年第3期12卷 29-42页

作者： Rui Yu Zhong Fang xi dai Hongming Weng School of Physics and Technology Wuhan University Wuhan 430072 China Beijing National Laboratory for Con-densed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China Collaborative Innovation Center of Quantum Matter Beijing 100190 China

Topological semimetals are newly discovered states of quantum matter, which have extended the con- cept of topological states from insulators to metals and attracted great research interest in recent years. In general, there are three kinds of topological semimetals, namely Dirac semimetals, Weyl semimet- als, and nodal line semimetals. Nodal line semimetals can be considered as precursor states for other topological states. For example, starting from such nodal line states, the nodal line structure might evolve into Weyl points, convert into Dirac points, or become a topological insulator by introducing the spin-orbit coupling （SOC） or mass term. In this review paper, we introduce theoretical materials that show the nodal line semimetal state, including the all-carbon Mackay-Terrones crystal （MTC）, anti-perovskite Cu3PdN, pressed black phosphorus, and the CaP3 family of materials, and we present the design principles for obtaining such novel states of matter.

关键词： topological states topological semimetals nodal line semimetal

GSTM1 and XRCC3 Polymorphisms:Effects on Levels of Aflatoxin B1-DNA Adducts

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Chinese Journal of Cancer Research 2009年第3期21卷 177-184页

作者： xi-dai Long Yun Ma Zhou-lin Deng Department of Pathology Youjiang Medical College for Nationalities Baise 533000 China Department of Pathology Guangxi Medical University Nanning 530021 China

Objective： Aflatoxin B1 （AFB1）, which can cause the formation of AFB1-DNA adducts, is a known human carcinogen. AFB1-exposure individuals with inherited susceptible carcinogen-metabolizing or repairing genotypes may experience an increased risk of genotoxicity. This study was designed to investigate whether the polymorphisms of two genes, the metabolic gene Glutathione S-transferase M1 （GSTM1） and DNA repair gene x-ray repair cross-complementing group 3 （XRCC3）, can affect the levels of AFB1-DNA adducts in Guangxi Population （n= 966） from an AFB1-exposure area. Methods： AFB1-DNA adducts were measured by ELISA, and GSTM1 and XRCC3 codon 241 genotypes were identified by PCR-RFLP. Results： The GSTM1-null genotype [adjusted odds ratio （OR） = 2.09; 95% confidence interval （CI） = 1.61-2.71] and XRCC3 genotypes with 241 Met alleles [i.e., XRCC3-TM and -MM, adjusted ORs （95% CI） were 1.43 （1.08-1.89） and 2.42 （1.13-5.22）, respectively] were significantly associated with higher levels of AFB1-DNA adducts. Compared with those individuals who did not express any putative risk genotypes as reference （OR = 1）, individuals featuring all of the putative risk genotypes did experience a significantly higher DNA-adduct levels （adjusted ORs were 2.87 for GSTM1-null and XRCC3-TM; 5.83 for GSTM1-null and XRCC3-MM）. Additionally, there was a positive joint effect between XRCC3 genotypes and long-term AFB1 exposure in the formation of AFB1-DNA adducts. Conclusion： These results suggest that individuals with susceptible genotypes GSTM1-null, XRCC3-TM, or XRCC3-MM may experience an increased risk of DNA damage elicited by AFB1 exposure.

关键词： Aflatoxin B1 (AFB1) AFB1-DNA adducts GSTM1 XRCC3 Polymorphism

Implementation of LDA+ Gutzwiller with Newton's method

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Chinese Physics B 2017年第1期26卷 391-398页

作者： Jian Zhang Ming-Feng Tian Guang-xi Jin Yuan-Feng Xu xi dai Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China LCP Institute of Applied Physics and Computational Mathematics Beijing 100088 China CAEP Software Center for High Performance Numerical Simulation Beijing 100088 China Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang 621900 China

In order to calculate the electronic structure of correlated materials, we propose implementation of the LDA＋Gutzwiller method with Newton＇s method. The self-consistence process, efficiency and convergence of calculation are improved dramatically by using Newton＇s method with golden section search and other improvement *** compare the calculated results by applying the previous linear mix method and Newton＇s method. We have applied our code to study the electronic structure of several typical strong correlated materials, including SrVO3, LaCoO3, and La2O3Fe2Se2. Our results fit quite well with the previous studies.

关键词： LDA+Gutzwiller strongly correlated electrons Newton's method

A new member of the topological semimetals family

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National Science Review 2017年第6期4卷 798-799页

作者： Hongming Weng Chen Fang Zhong Fang xi dai Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of Sciences Collaborative Innovation Center of Quantum Matter

In topological semimetals(TSMs),the quasi-particle excitations of electrons can be described by the Dirac or Weyl equation,mimicking the elusive massless Dirac or Weyl fermions in the low-frequency regime as emergent ... 详细信息

关键词： A new member of the topological semimetals family DSM WSM

Acceleration of the Stochastic Analytic Continuation Method via an Orthogonal Polynomial Representation of the Spectral Function

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Chinese Physics Letters 2013年第9期30卷 1-4页

作者： WU Quan-Sheng WANG Yi-Lin FANG Zhong dai xi Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190

Stochastic analytic continuation is an excellent numerical method for analytically continuing Green’s functions from imaginary frequencies to real frequencies,although it requires significantly more computational time than the traditional MaxEnt *** develop an alternate implementation of stochastic analytic continuation which expands the dimensionless field𝑜n(x)introduced by Beach using orthogonal *** use the kernel polynomial method(KPM)to control the Gibbs oscillations associated with truncation of the expansion in orthogonal *** KPM variant of stochastic analytic continuation delivers improved precision at a significantly reduced computational cost.

关键词： continuation analytic stochastic