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Machine learning the Hubbard U parameter in DFT+U using Bayesian optimization

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npj Computational Materials 2020年第1期6卷 163-168页

作者： Maituo Yu Shuyang Yang Chunzhi Wu Noa Marom department of Materials science and Engineering Carnegie Mellon UniversityPittsburghPA 15213USA department of physics Carnegie Mellon UniversityPittsburghPA 15213USA department of Chemistry Carnegie Mellon UniversityPittsburghPA 15213USA

Within density functional theory(DFT),adding a Hubbard U correction can mitigate some of the deficiencies of local and semi-local exchange-correlation functionals,while maintaining computational ***,the accuracy of DFT+U largely depends on the chosen Hubbard U *** propose an approach to determining the optimal U parameters for a given material by machine *** Bayesian optimization(BO)algorithm is used with an objective function formulated to reproduce the band structures produced by more accurate hybrid *** approach is demonstrated for transition metal oxides,europium chalcogenides,and narrow-gap *** band structures obtained using the BO U values are in agreement with hybrid functional ***,comparison to the linear response(LR)approach to determining U demonstrates that the BO method is superior.

关键词： optimization Hubbard parameter

Physical and toxicological profiles of human IAPP amyloids and plaques

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science Bulletin 2019年第1期64卷 26-35页

作者： Aleksandr Kakinen Yunxiang Sun Ibrahim Javed Ava Faridi Emily H.Pilkington Pouya Faridi Anthony W.Purcell Ruhong Zhou Feng Ding Sijie Lin Pu Chun Ke Thomas P.Davis ARC Centre of Excellence in Convergent Bio-Nano science and Technology Monash Institute of Pharmaceutical Sciences Monash University department of physics and Astronomy Clemson University College of Environmental science and Engineering Shanghai Institute of Pollution Control and Ecological Security Biomedical Multidisciplinary Innovation Research Institute Shanghai East Hospital Tongji University Infection and Immunity Program & department of Biochemistry and Molecular Biology Biomedicine Discovery Institute Monash University IBM Thomas J.Watson Research center department of Chemistry Columbia University

Although much has been learned about the fibrillization kinetics, structure and toxicity of amyloid proteins, the properties of amyloid fibrils beyond the saturation phase are often perceived as chemically and biologically inert, despite evidence suggesting otherwise. To fill this knowledge gap, we examined the physical and biological characteristics of human islet amyloid polypeptide(IAPP) fibrils that were aged up to two months. Not only did aging decrease the toxicity of IAPP fibrils, but the fibrils also sequestered fresh IAPP and suppressed their toxicity in an embryonic zebrafish model. The mechanical properties of IAPP fibrils in different aging stages were probed by atomic force microscopy and sonication, which displayed comparable stiffness but age-dependent fragmentation, followed by self-assembly of such fragments into the largest lamellar amyloid structures reported to date. The dynamic structural and toxicity profiles of amyloid fibrils and plaques suggest that they play active, long-term roles in cell degeneration and may be a therapeutic target for amyloid diseases.

关键词： IAPP Amyloid Plaque Self assembly Toxicity

Precision Calculations of Atomic Polarizabilities： A Relevant Physical Quantity in Modern Atomic Frequency Standard

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Chinese physics Letters 2010年第6期27卷 78-81页

作者： GAO Xiang LI Jia-Ming department of physics Shanghai Jiao Tong University Shanghai 200240 department of physics and Key Laboratory of Atomic and Molecular Nanosciences of Ministry of Education Tsinghua University Beijing 100084

Electric dipole polarizabilities of atoms are very important in many different physical applications, such as the precision atomic frequency standard. Calculations of these properties are very important and challenging. We propose a calculation strategy to calculate the frequency dependent dipole polarizabilities with high precision variationally by using a set of high quality orbital bases where the electron correlations can be taken into account adequately. The static polarizabilitiez of the ground state of Na are calculated accurately by such a method and can be compared with precision experiment measurement directly. The calculation result is in excellent agreement with the available experimental measurements within about 0.1~, which demonstrates the validity of our strategy. Our calculation strategy has a wide usage, not only in polarizibilies, but also in other fields such as theoretical treatment of electron-atom scattering processes. Using the same orbital bases, we carry out precision calculation of Na- affinities. Our calculated affinity is in excellent agreement with precision laser spectroscopy measurements within 0. 1%.

关键词： PHYSICAL constants ATOMIC frequency standards DIPOLE moments POLARIZABILITY (Electricity) VARIATIONAL principles ATOMIC orbitals SCATTERING (physics) LASER spectroscopy

Polarization pinning at antiphase boundaries in multiferroic YbFeO_(3)

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Chinese physics B 2024年第11期33卷 39-45页

作者： Guodong Ren Pravan Omprakash Xin Li Yu Yun Arashdeep S.Thind Xiaoshan Xu Rohan Mishra Institute of Materials science and Engineering Washington University in St.LouisSt.LouisMO 63130USA department of physics and Astronomy University of NebraskaLincolnNE 68588USA department of Mechanical Engineering & Mechanics Drexel UniversityPhiladelphiaPA 19104-2875USA Nebraska center for Materials and Nanoscience University of NebraskaLincolnNE 68588USA department of Mechanical Engineering and Material science Washington University in St.LouisSt.LouisMO 63130USA

The switching characteristics of ferroelectrics and multiferroics are influenced by the interaction of topological defects with domain *** report on the pinning of polarization due to antiphase boundaries in thin films of the multiferroic hexagonal YbFeO_(3).We have directly resolved the atomic structure of a sharp antiphase boundary(APB)in YbFeO_(3) thin films using a combination of aberration-corrected scanning transmission electron microscopy(STEM)and total energy calculations based on density-functional theory(DFT).We find the presence of a layer of FeO_(6) octahedra at the APB that bridges the adjacent *** imaging shows a reversal in the direction of polarization on moving across the APB,which DFT calculations confirm is structural in nature as the polarization reversal reduces the distortion of the FeO_(6) octahedral layer at the *** APBs in hexagonal perovskites are expected to serve as domain-wall pinning sites and hinder ferroelectric switching of the domains.

关键词： hexagonal ferrites ferroelectric multiferroic topological defect STEM

α-Fe_2O_3 nanoparticles:An efficient,inexpensive catalyst for the one-pot preparation of 3,4-dihydropyrano[c]chromenes

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Chinese Chemical Letters 2011年第2期22卷 143-146页

作者： H.Nagabhushana S.Sandeep Saundalkar L.Muralidhar B.M.Nagabhushana C.R.Girija D.Nagaraja M.A.Pasha V.P.Jayashankara department of PG Studies in physics and Research University Science CollegeTumkur UniversityTumkur 572103India department of Chemistry SSMRV CollegeChemistry Research CenterBangalore 560041India department of Chemistry M.S.Ramaiah Institute of TechnologyBangalore 560054India department of PG Studies in Chemistry and Research University Science CollegeTumkur UniversityTumkur 572103India department of Chemistry Central College CampusBangalore UniversityBangalore 560001India

This paper describes the combustion synthesis ofα-Fe2O3 nanopowder at much lower temperature and its catalytic activity for the one-pot preparation of 3,4-dihydropyrano[c]*** combustion derivedα-Fe_2O_3 nanopowder was characterized by powder X-ray diffraction（PXRD）,Braunauer,Emmett and Teller（BET） surface area,scanning electron microscopy（SEM） and Fourier transform infrared spectroscopy（FTIR）.Highly efficient,three-component condensation of aromatic aldehyde,malanonitrile and 4- hydroxycoumarin catalyzed byα-Fe2O3 nanoparticles at room temperature is *** method offers an excellent alternative to the synthesis of 3,4-dihydropyrano[c]*** reactions are rapid,clean,and the products with good yield and high purity.

关键词： α-Fe2O3 nanopowder One pot three-component condensation Aromatic aldehyde Malanonitrile 4-Hydroxycoumarin

A Molecular Dynamics Simulation of CaSiO3 Melt Under an Electric Field

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Chinese physics Letters 2000年第4期17卷 279-281页

作者： HUANG Shi-Ping YOU Jing-Pin JIANG Guo-Chang F.Yoshida XU Kuang-Di Shanghai Enhanced Laboratory of Ferro-metallurgy Shanghai Universityj Shanghai 200072 department of physics Shiga University of Medical ScienceShiga 520-2192Japan

The results of a molecular dynamics(MD)simulation are presented for CaSiO3 melt under an electric *** two-body interaction potential is adopted in the simulation,with parameters chosen so that the calculated static structure is consistent with results of high temperature x-ray *** is found that the MD results for the heat capacity at constant volume,the self-diffusion coefficient and the electrical conductivity change greatly when the electric field is over 500 MV/*** is given on these results,together with the frequency-dependent electrical conductivity.

关键词： field electrical Molecular

Phase transformation behavior of a dual-phase nanostructured Fe-Ni-B-Si-P-Nb metallic glass and its correlation with stress-impedance properties

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Rare Metals 2023年第8期42卷 2757-2766页

作者： Jia-Cheng Ge Ai-Hua Liu Zhen-Duo Wu Yao Gu Yu-Bin Ke An-Ding Wang Yang Ren Song Tang Hui-Qiang Ying He Zhu Xun-Li Wang Si Lan Herbert Gleiter Institute of Nanoscience School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China department of physics City University of Hong KongHong Kong999077China City university of Hong Kong(Dongguan) Dongguan 523000China center for Neutron Scattering City University of Hong Kong Shenzhen Research InstituteShenzhen 518057China Spallation Neutron Source science center Dongguan 523803China Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering science and Technology Dongguan 523803China School of Materials science and Engineering Dongguan University of TechnologyDongguan 523808China

A study of the phase transformation process of a Fe-Ni-B-Si-P-Nb metallic glass using a suite of advanced characterization tools is *** electron microscopy(TEM)and small angle neutron scattering(SANS)experiments show that the as-spun metallic glass ribbon has a dual-phase structure with bcc nanoclusters of a size of 2-3 *** situ high-energy X-ray diffraction(XRD)reveals a three-stage crystallization process when heating the metallic glass into supercooled liquid *** isothermal annealing experiment shows the nanoclusters grow instantly without *** easy formation and phase stability of the nanoclusters are due to the low interfacial energy between the amorphous matrix and clusters,as real space analysis shows that the nanoclusters and the amorphous matrix share similar short-to-mediumrange *** further find that the dual-phase structure reduces local magneto-anisotropy and enhances effective magnetic permeability,resulting in an excellent stressimpedance effect without sacrificing *** work sheds light on the structure-property engineering of soft magnetic metallic glasses and provides a foundation for developing novel magnetic functional materials with nanostructured dual-phases.

关键词： Soft-magnetic property Metallic glass Phase transformation Synchrotron and neutron scattering Stressimpedance(SI)

A Model to Evaluate the Device-Level Performance of Thermoelectric Cooler with Thomson Effect Considered

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Journal of Thermal science 2022年第3期31卷 712-726页

作者： GONG Tingrui GAO Lei WU Yongjia TAN Haoshu QIN Feng XIN Xiong SHEN Limei LI Juntao MING Tingzhen Microsystem&Terahertz Research center China Academy of Engineering PhysicsChengdu610200China Institute of Electronic Engineering China Academy of Engineering PhysicsMianyang621999China School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan430070China department of Refrigeration&Cryogenics Engineering Huazhong University of Science and TechnologyWuhan430074Chin

In this paper,a one-dimensional thermodynamic model was developed to evaluate the device-level performance of thermoelectric cooler(TEC)with the Thomson effect,contact resistance,gap heat leakage,heat sink,and heat load taken into *** model was generalized and simplified by introducing dimensionless *** measurements showed good agreement with analytical *** parametric analysis indicated that the influence of the Thomson effect on cooling capacity continued to expand with increasing current,while the effect on COP hardly changed with *** thermal contact resistance was beneficial to obtain lower hot-junction temperature,which can even reduce 2 K compared with the electrical contact resistance in the case *** gap heat leakage was a negative factor affecting the cooling *** the thermal resistance of the heat sink was small,the negative effect of heat leakage on performance would be further *** enhancement of heat load temperature would increase the cooling power of the *** example,an increase of 5 K in heat load can increase the cooling capacity by about 4%.However,once the current exceeded the optimum value,the raising effect on the cooling power would be *** research can provide an analytical approach for the designer to perform trade studies to optimize the TEC system.

关键词： thermoelectric cooler thermodynamic model Thomson effect contact resistance device-level performance

Modulated hydrocarbon distribution of gasoline deriving from butene conversion in the presence of syngas

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Journal of Energy Chemistry 2022年第10期31卷 416-421,I0010页

作者： Yi Ding Feng Jiao Xiulian Pan Xinhe Bao department of Chemical physics University of Science and Technology of ChinaHefei 230026AnhuiChina State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy2011-Collaborative Innovation Center of Chemistry for Energy MaterialsDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina university of Chinese Academy of sciences Beijing 100049China

With the expansion of butene production capacity,clean and efficient conversion of mixed butene attracts increasing *** we report direct co-conversion of butene and syngas to highquality gasoline enabled by a bifunctional OXZEO catalyst comprising ZnCrO_(x) oxide and ZSM-5 zeolite.A gasoline selectivity of 71.6% at 98.1% butene conversion and 26.2% CO conversion have been obtained under the reaction conditions of 360℃,3 MPa and 3000 mL g^(-1) h^(-1).The space time yield of gasoline of0.25 g·g^(-1) h^(-1) is ***,the presence of syngas can effectively facilitate iso-paraffin production while hindering the formation of *** is attributed to the prohibited hydrogen transfer aromatization process of butene on ZSM-5 in the presence of *** rthermore,the formation of isomers of gasoline range hydrocarbons is favored because the active intermediates generated from CO/H_(2) activation over ZnCrO_(x) oxide could react with butene over ZSM-5 ***,the product distribution among gasoline range hydrocarbons is modulated with reduced heavy aromatics and improved iso-paraffins,which is desirable for application as *** provides an alternative environmentally friendly technology to utilize still increasing mixed butene.

关键词： Butene utilization Bifunctional catalysts OXZEO Syngas conversion Gasoline