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61 108/1 戰略所 李大中 副教授 期刊論文 發佈 川普的印太戰略與美中戰略競爭 , [108-1] :川普的印太戰略與美中戰略競爭期刊論文川普的印太戰略與美中戰略競爭李大中印太戰略;川普;美中關係;戰略競爭者軍事社會科學專刊 15, p.3-14自 2017 年 10 月以來,美國川普政府所推出的印太倡議,反映出美國對於印太區域的關注,此一戰略的最終目標,在於抑制中國大陸的崛起與確保美國的領導地位。而自 2018 年年中迄今,美中關係的急遽惡化,不僅展現在貿易衝突,更涉及至政治與軍事等領域。無庸置疑,在印太架構下,川普政府下定決心在印太戰略的大架構下重塑美國的對中政策,一方面,華府將北京定位為急切改變區域現狀的修正主義強權,另一方面,川普也視中國大陸為戰略競爭者,意圖挑戰與減損美國在此區域的權力、利益與影響力。本文的主要目的在於探討川普採取更強勢與衝突性對中政策的背後動機,並分析其對印太戰略所產生的複雜影響。zh_TW2664-2700國內否TWN
62 104/2 統計系 陳淑嬌 助理教授 期刊論文 發佈 從韓國科技評估制度探討科技風險治理之重要性 , [104-2] :從韓國科技評估制度探討科技風險治理之重要性期刊論文從韓國科技評估制度探討科技風險治理之重要性陳淑嬌科技評估;風險治理臺灣經濟研究月刊 39(4), p.14-20zh_TW1023-8867國內否TWN
63 105/1 統計系 陳淑嬌 助理教授 期刊論文 發佈 Research on the Elderly Living Industry Development on the Assessment Approach of Regional Economic Impact , [105-1] :Research on the Elderly Living Industry Development on the Assessment Approach of Regional Economic Impact期刊論文Research on the Elderly Living Industry Development on the Assessment Approach of Regional Economic ImpactHilary Cheng; Yi-Chuan Lu; Shu-Chiao ChenAging Society;Elderly Living Industry;Input-Output Analysis;Regional Computable General Equilibrium ModelApplied Science and Management Research 3(1), p.28-45The aging society brings changes to the living model and family structure and also triggers new industry needs and issues. Taiwan's health maintenance residence develops towards the project in combination with medical system in recent years. The layout of health maintenance, customized programming hardware as well as the care services has become a trend. To this end, the public and private sectors are successively devoting resources to this market. This paper plans to use the regional computable general equilibrium model (RCGE) as the tool to make exploration on the assessment m
64 108/1 化材系 林國賡 教授 期刊論文 發佈 Mass transfer enhancement in double-pass concentric-tube mass exchangers under sinusoidal wall fluxes with external recycle , [108-1] :Mass transfer enhancement in double-pass concentric-tube mass exchangers under sinusoidal wall fluxes with external recycle期刊論文Mass transfer enhancement in double-pass concentric-tube mass exchangers under sinusoidal wall fluxes with external recycleChii-Dong Ho; Gwo-Geng Lin; Jing-Min Tang; Li-Chien Liu; Li-Pang Lin; Jr-Wei TuSinusoidal Wall Fluxes;Orthogonal Expansion Technique;Double-pass Operation;Mass Exchanger;RecycleJournal of Applied Science and Engineering, Vol. 22, No.3, pp. 403-412The influences of external recycle at the ends on double-pass laminar counterflow concentrictube mass exchangers with sinusoidal wall flux distribution are investigated analytically. An analytical method is proposed to obtain a general solution by using the complex functions in combining the original boundary value problem into an ordinary differential equation with the aid of Frobenius method. Theoretical results show that a suitable adjustment of the permeable-barrier position can effectively
65 108/1 歐研所 陳麗娟 教授 期刊論文 發佈 『英國脫歐』後歐盟法與英國法適用爭議之研究 , [108-1] :『英國脫歐』後歐盟法與英國法適用爭議之研究期刊論文『英國脫歐』後歐盟法與英國法適用爭議之研究中文陳麗娟歐盟;英國脫歐;單一市場;歐洲金融市場貿易政策論叢 第31期 頁17-42zh_TW國內陳麗娟是TWN
66 106/2 國企系 曾忠蕙 副教授 期刊論文 發佈 品牌熟悉度、網路口碑與抽獎可控性對賭博式價格促銷活動之影響 , [106-2] :品牌熟悉度、網路口碑與抽獎可控性對賭博式價格促銷活動之影響期刊論文品牌熟悉度、網路口碑與抽獎可控性對賭博式價格促銷活動之影響曾忠蕙; 王又鵬; 吳奕瑩賭博式價格促銷;品牌熟悉度;網路口碑;抽獎可控性;品牌轉換意願創新與管理, 14卷2期, 1-20頁近年來零售業者推出了一種特別的促銷方式,此種促銷是根據抽獎方式所創造的不確定賭博結果來獲得價格折扣,折扣幅度從89折、79折、69折到1元不等,此種促銷稱作賭博式價格促銷。本研究便是在賭博式價格促銷基礎下,探討品牌熟悉度、網路口碑與抽獎可控性對消費者之參與意願與品牌轉換意願之影響。研究方法以2(品牌熟悉度的高或低)X2(網路口碑的正面或負面)X2(抽獎可控性的高或低)共8組受測者間實驗設計之問卷在網路間卷平台進行發放,回收有效問卷共212份,獲得以下結論:(1)賭博式價格促銷下,品牌熟悉度高之品牌轉換意願會顯著地高於品牌熟悉度低之品牌轉換意願。(2)賭博式價格促銷下,抽獎可控性高之參與意願會顯著地高於抽獎可控性低之參與意願。zh_TW國內是TWN
67 107/2 教科系 沈俊毅 副教授 期刊論文 發佈 Students' Acceptance of Gamification in Higher Education , [107-2] :Students' Acceptance of Gamification in Higher Education期刊論文Students' Acceptance of Gamification in Higher EducationChih-Hung Chung; Chunyi Shen; Yu-Zhen QiuGamification;Higher Education;Students' AcceptanceInternational Journal of Game-Based Learning (IJGBL), 9(2), 1–19Gamification provides a practical approach to improving learning processes, especially the learner's motivation. However, little research has been conducted on student intentions to use gamification in higher education. Therefore, this study explored the gamification in higher educational courses by collecting surveys and discusses the factors influencing the acceptance of gamification in higher education. Based on the PLS-SEM results, students should take initial game-based learning content to be more familiar with gamification; furthermore, they could have a positive experience so that they would increase their intention. Performance expectancy is the most important factors influencing a student to accept gamification
68 108/1 航太系 牛仰堯 教授 期刊論文 發佈 A development of a sharp interface AUSMD scheme for an incompressible preconditiong multi-fluid model , [108-1] :A development of a sharp interface AUSMD scheme for an incompressible preconditiong multi-fluid model期刊論文A development of a sharp interface AUSMD scheme for an incompressible preconditiong multi-fluid modelYang-Yao Niu; Chia-Hung WengPreconditiong AUSM;Incompressible Flow;Interface Capturing;MUSCL+THINCComputers & Fluids Volume 192, 15 October 2019, 104269In this study, the paper first proposes a sharp-interface cell interface variable reconstruction to solve the preconditioning incompressible multi-fluid flow model using the AUSMD scheme. Here, the preconditioning matrix modified from the Chorin's artificial compressibility makes the incompressible multi-fluid equations to be hyperbolic. Therefore, a simple AUSMD type flux-splitting with the MUSCL+THINC (Tangent of Hyperbola for Interface Capturing) type cell interface variable reconstruction is used to maintain the preservation of sharp interface evolutions of the multi-fluid simulation. A high-resolution interpolation MUSCL+THINC,
69 108/1 機械系 康尚文 教授 期刊論文 發佈 Manufacture and Test of a High Temperature Heat Pipe , [108-1] :Manufacture and Test of a High Temperature Heat Pipe期刊論文Manufacture and Test of a High Temperature Heat PipeShung-Wen Kang, Huan-Ming Yeh , Meng-Chang Tsai , His-Hsiang WuHigh Temperature Heat Pipe, Metal Sodium, Stainless Steel ScreenJournal of Applied Science and Engineering, Vol. 22, No. 3, pp. 493-499Heat pipe play an important role in high temperature energy transfer system and storage system. It can be applied to the areas such as solar energy storage system and waste heat recovery. High temperature heat pipes with 420 mm in length, 13 mm in outer diameter and 2 mm in tube thickness have been developed and tested. The device was made of Inconel 600 equipped with a 316 stainless steel 100 mesh wick. The working fluid was metal sodium with a filling ratio of 10% (2.86 g). Heat pipes start-up and thermal characteristics were investigated at different orientations with slopes of -15, 0, +45 and +90 while heat sink temperatures were kept at 27 C air environment. The evaporator temper
70 108/1 財金系 李沃牆 教授 期刊論文 發佈 人民幣破7 貿易及貨幣戰升溫 , [108-1] :人民幣破7 貿易及貨幣戰升溫期刊論文人民幣破7 貿易及貨幣戰升溫李沃牆觀察月刊 73, p.64-65人民幣貶破7後,不僅全球股匯震盪,川普還指控中國大陸操縱匯率;揚言再提高關稅,甚至施壓聯準會降息。準此以觀,一場貨幣戰正山雨欲來,貿易戰恐將升級,實不容小覷。 8月5日受貿易戰及香港「三罷」影響,人民幣對美元中間價調降229點,至6.9225元;中間價甫一公布,離岸人民幣應聲跌破7元關卡,來到7.0221元,創金融海嘯以來新低。而台幣至午盤重貶2.33角,暫收在31.609元,交易量亦暴增。在岸、離岸人民幣雙雙跳水「破7」關卡,結果引發美股大跌,全球股市亦難倖免,仿佛2015年8月11(811事件)人民幣大貶值,釀成全球股災的翻版;但目前正值美中貿易戰當頭,尤為敏感。8月12 日,中國外匯交易中心公告,人民幣對美元中間價下調75點,報7.0211。中間價連六日下調,連三日跌破7關卡。zh_TW國內否TWN
71 107/2 未來學所 紀舜傑 副教授 期刊論文 發佈 馬來西亞的國家認同多元與單一的取捨 , [107-2] :馬來西亞的國家認同多元與單一的取捨期刊論文馬來西亞的國家認同多元與單一的取捨紀舜傑馬來人;原生論;建構論;多層次因果分析;Malaysia;Primordialism;Constructionism;CLA台灣國際研究季刊,第 15卷第 1期,頁97-116本文主要希望以上述原生論與建構論的脈絡,檢視馬來西亞的國家認同議題,並探究主要的形塑因素。並使用未來學的多層次因果分析法進行剖析。結果發現在表象層的問題是族群多元、宗教多元、語言多元、不平等對立。系統層是隔離、多元性與多元文化。世界觀/論述則是伊斯蘭國度、後殖民體制。隱喻/迷思乃是一個國家、一個民族、一個宗教;華僑、華人、華裔的爭議。我們發現憲法上的不平等規定是國家認同的癥結所在,那修憲是否應該被慎重考慮。然而這是禁忌議題,加上馬來西亞的伊斯蘭化,讓族群融合加上宗教信仰的難解要素,似乎也只能靜靜地期待真正脫胎換骨的馬來西亞誕生。zh_TW國內是TWN
72 107/2 未來學所 紀舜傑 副教授 期刊論文 發佈 義大利的公投─歐盟因素 , [107-2] :義大利的公投─歐盟因素期刊論文義大利的公投─歐盟因素Referendums in Italy: European Elements紀舜傑義大利公投;多層次因果分析;民粹主義;Italian Referendum;Causal Layered Analysis;European Union台灣國際研究季刊 15(2), p.145-165義大利是少數西歐國家中允許由人民直接發動公投的國家,因而公投經驗豐富,所有公投次數在西歐民主國家中僅次於瑞士,並經常被類爲公投研究的案例。本文主要探討重點在於認識義大利公投之制度設計,執行情形,並探討近年來最引人注目的2016憲政公投,特別是夾雜在那次公投中的歐盟因素,最後則以未來學的多層次因果分析法,對義大利的公投進行深度分析。我們發現許多導致2016年公投的表面問題,例如政府施政效率不彰、經濟衰退、日益嚴重的難民湧入問題。在系統層我們則看到義大利憲政體制造成的立法延宕,內閣不穩,以及決策受限歐盟規範的制度性原因與結果。在世界觀與論述方面,2016年公投除了是對憲政改革的集體意志表達外,因爲倫齊如果下台後,右派民粹傾向的五星行動黨可能組閣,於是世人便將此公投視爲義大利對與歐盟未來關係的一次表態,歐盟因素便被加入分析討論中,我們也從許多實證調查資料中發現義大利對歐盟的較負面的態度。最後的迷思或隱喻部分,我們提出是否以民粹風潮來看待義大利2016公投的結果乃爲過度簡化與誤導。 Italy, indeed, is a country with plenty of experiences in upholding referendums. This article is to comprehend its institutional designs and practices in a long period of time. Moreover, we try to use 2016 Referendum as a case study to explore the influence of European Union in all aspects. In the end we use Causal Layered Analysis to dissect and conclude the complicated issues invol
73 108/1 財金系 李沃牆 教授 期刊論文 發佈 中國科創板的發展前景及影響 , [108-1] :中國科創板的發展前景及影響期刊論文中國科創板的發展前景及影響李沃牆會計研究月刊 第406期, pp.18-22有「中國那斯達克」之稱的中國股市新板塊-科創板,首批25家公司在今(2019)年7 月22 日於上海證券交易所開市。科創板是中國國家主席習近平去(2018)年11 月5 日在首屆中國國際進口博覽會開幕式宣布的政策,從提出到開市僅用了259 天,速度之快,前所未有。zh_TW國內否TWN
74 105/2 物理系 李啟正 助理教授 期刊論文 發佈 G-type magnetic order in ferropnictide CuxFe1-yAs induced by hole doping on As sites , [105-2] :G-type magnetic order in ferropnictide CuxFe1-yAs induced by hole doping on As sites期刊論文G-type magnetic order in ferropnictide CuxFe1-yAs induced by hole doping on As sitesT. Zou; C. C. Lee; W. Tian: H. B. Cao; M. Zhu; B. Qian; C. R. dela Cruz; W. Ku; Z. Q. Mao; X. KePHYSICAL REVIEW B 95, 054414Strong antiferromagnetic (AFM) correlation has long been postulated to be closely related to the occurrence of unconventional high-temperature superconductivity observed in the cuprates, heavy fermions, and organic superconductors. The recently discovered Fe-based superconductors add another interesting member to the list. However, insufficient attention has been paid to the versatile nature of the magnetic correlation in these materials: some showing stripe (C-type) order, others double stripe (E-type) or block AFM order instead, implying potentially richer structures of the superconducting order. Here we report the observation of yet another AFM correlation in the family: a G-type AFM order as
75 105/2 物理系 李啟正 助理教授 期刊論文 發佈 Magnetic-tunnelling-induced Weyl node annihilation in TaP , [105-2] :Magnetic-tunnelling-induced Weyl node annihilation in TaP期刊論文Magnetic-tunnelling-induced Weyl node annihilation in TaPCheng-Long Zhang; Su-Yang Xu; C. M. Wang; Ziquan Lin; Z. Z. Du; Cheng Guo; Chi-Cheng Lee; Hong Lu; Yiyang Feng; Shin-Ming Huang; Guoqing Chang; Chuang-Han Hsu; Haiwen Liu; Hsin Lin; Liang Li; Chi Zhang; Jinglei Zhang; Xin-Cheng Xie; Titus Neupert; M. Zahid Hasan; Hai-Zhou Lu; Junfeng Wang; Shuang JiaNature Physics 13, 979Weyl nodes are topological objects in three-dimensional metals. Whereas the energy of the lowest Landau band of a conventional Fermi pocket increases with magnetic field due to the zero-point energy (1/2ℏω), the lowest Landau band of Weyl cones stays at zero energy unless a strong magnetic field couples Weyl fermions of opposite chirality. In the Weyl semimetal TaP, which possesses two types of Weyl nodes (four pairs of W1 and eight pairs of W2 nodes), we observed such a magnetic coupling between the electron pockets arising from the W1 Weyl fermions. A
76 106/1 物理系 李啟正 助理教授 期刊論文 發佈 Atomic-scale visualization of surface-assisted orbital order , [106-1] :Atomic-scale visualization of surface-assisted orbital order期刊論文Atomic-scale visualization of surface-assisted orbital orderHowon Kim; Yasuo Yoshida; Chi-Cheng Lee; Tay-Rong Chang; Horng-Tay Jeng; Hsin Lin; Yoshinori Haga; Zachary Fisk; Yukio HasegawaScience Advances Vol. 3, no. 9 eaao0362Orbital-related physics attracts growing interest in condensed matter research, but direct real-space access of the orbital degree of freedom is challenging. We report a first, real-space, imaging of a surface-assisted orbital ordered structure on a cobalt-terminated surface of the well-studied heavy fermion compound CeCoIn5. Within small tip-sample distances, the cobalt atoms on a cleaved (001) surface take on dumbbell shapes alternatingly aligned in the [100] and [010] directions in scanning tunneling microscopy topographies. First-principles calculations reveal that this structure is a consequence of the staggered dxz-dyz orbital order triggered by enhanced on-site Coulomb interaction at the surfac
77 106/1 物理系 李啟正 助理教授 期刊論文 發佈 Topological superconductor in quasi-one-dimensional Tl2-xMo6Se6 , [106-1] :Topological superconductor in quasi-one-dimensional Tl2-xMo6Se6期刊論文Topological superconductor in quasi-one-dimensional Tl2-xMo6Se6Shin-Ming Huang, Chuang-Han Hsu, Su-Yang Xu, Chi-Cheng Lee, Shiue-Yuan Shiau, Hsin Lin, and Arun BansilPHYSICAL REVIEW B 97, 014510We propose that the quasi-one-dimensional molybdenum selenide compound Tl 2 − x Mo 6 Se 6 is a time-reversal-invariant topological superconductor induced by intersublattice pairing, even in the absence of spin-orbit coupling (SOC). No noticeable change in superconductivity is observed in Tl-deficient ( 0 ≤ x ≤ 0.1 ) compounds. At weak SOC, the superconductor prefers the triplet d vector lying perpendicular to the chain direction and two-dimensional E2u symmetry, which is driven to a nematic order by spontaneous rotation symmetry breaking. The locking energy of the d vector is estimated to be weak and hence the proof of its direction would rely on tunneling or phase-sensitive measurements.en_US國外SCI;是USA
78 107/1 物理系 李啟正 助理教授 期刊論文 發佈 Atomic Structure and Local Electronic States of Single Pt Atoms Dispersed on Graphene , [107-1] :Atomic Structure and Local Electronic States of Single Pt Atoms Dispersed on Graphene期刊論文Atomic Structure and Local Electronic States of Single Pt Atoms Dispersed on GrapheneKenji Yamazaki, Yosuke Maehara, Chi-Cheng Lee, Jun Yoshinobu, Taisuke Ozaki, and Kazutoshi GoharaJ. Phys. Chem. C 122(48), p.27292-27300In single-atom catalysis, the atomic structure and local electronic states of single atoms on a supporting material remain a fundamental question. We experimentally and theoretically solved these problems for single Pt atoms dispersed on freestanding graphene using plasma sputtering. Electron microscopy revealed the atomic arrangements of Pt atoms binding to carbon atoms at the step edges of nanographene flakes. X-ray photoelectron spectroscopy revealed a large binding energy shift of the Pt 4f state of a single Pt atom. First-principles calculations elucidated that the Pt 5dxy-orbital in the step edge plays a crucial role in the formation of chemical bonds to C atoms and in the co
79 107/2 物理系 李啟正 助理教授 期刊論文 發佈 Non-saturating quantum magnetization in Weyl semimetal TaAs , [107-2] :Non-saturating quantum magnetization in Weyl semimetal TaAs期刊論文Non-saturating quantum magnetization in Weyl semimetal TaAsCheng-Long Zhang; C. M. Wang, Zhujun Yuan; Xitong Xu; Guangqiang Wang; Chi-Cheng Lee; Li Pi; Changying Xi; Hsin Lin; Neil Harrison; Hai-Zhou Lu; Jinglei Zhang; Shuang JiaMagnetic properties and materials;Topological insulatorsNature Communications 10, 1028Detecting the spectroscopic signatures of relativistic quasiparticles in emergent topological materials is crucial for searching their potential applications. Magnetometry is a powerful tool for fathoming electrons in solids, by which a clear method for discerning relativistic quasiparticles has not yet been established. Adopting the probes of magnetic torque and parallel magnetization for the archetype Weyl semimetal TaAs in strong magnetic field, we observed a quasi-linear field dependent effective transverse magnetization and a non-saturating parallel magnetization when the system enters the quantum limit. Disti
80 107/2 物理系 李啟正 助理教授 期刊論文 發佈 Scanning tunneling microscopy on cleaved Mn3Sn(0001) surface , [107-2] :Scanning tunneling microscopy on cleaved Mn3Sn(0001) surface期刊論文Scanning tunneling microscopy on cleaved Mn3Sn(0001) surfaceHung-Hsiang Yang, Chi-Cheng Lee, Yasuo Yoshida, Muhammad Ikhlas, Takahiro Tomita, Agustinus Nugroho, Taisuke Ozaki, Satoru Nakatsuji, and Yukio HasegawaElectronic properties and materials Surfaces;interfaces and thin filmsScientific Reports 9, 9677We have studied in-situ cleaved (0001) surfaces of the magnetic Weyl semimetal Mn3Sn by low-temperature scanning tunneling microscopy and spectroscopy (STM/S). It was found that freshly cleaved Mn3Sn surfaces are covered with unknown clusters, and the application of voltage pulses in the tunneling condition was needed to achieve atomically flat surfaces. STM topographs taken on the flat terrace show a bulk-terminated 1 × 1 honeycomb lattice with the Sn site brightest. First-principles calculations reveal that the brightest contrast at the Sn site originates from the surrounding surface Mn d orbitals. Tunneling spectrosco
81 103/2 物理系 李啟正 助理教授 期刊論文 發佈 A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class , [103-2] :A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class期刊論文A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs classShin-Ming Huang; Su-Yang Xu; Ilya Belopolski; Chi-Cheng Lee; Guoqing Chang; BaoKai Wang; Nasser Alidoust; Guang Bian; Madhab Neupane; Chenglong Zhang; Shuang Jia; Arun Bansil; Hsin Lin; M. Zahid HasanQuantum Hall;Theoretical physicsNature Communications 6, 7373Weyl fermions are massless chiral fermions that play an important role in quantum field theory but have never been observed as fundamental particles. A Weyl semimetal is an unusual crystal that hosts Weyl fermions as quasiparticle excitations and features Fermi arcs on its surface. Such a semimetal not only provides a condensed matter realization of the anomalies in quantum field theories but also demonstrates the topological classification beyond the gapped topological insulators. Here, we identify a topological Weyl semimetal state in
82 104/1 物理系 李啟正 助理教授 期刊論文 發佈 Discovery of a Weyl Fermion semimetal and topological Fermi arcs , [104-1] :Discovery of a Weyl Fermion semimetal and topological Fermi arcs期刊論文Discovery of a Weyl Fermion semimetal and topological Fermi arcsSu-Yang Xu; Ilya Belopolski; Nasser Alidoust; Madhab Neupane; Guang Bian; Chenglong Zhang; Raman Sankar; Guoqing Chang; Zhujun Yuan; Chi-Cheng Lee; Shin-Ming Huang; Hao Zheng; Jie Ma; Daniel S. Sanchez; BaoKai Wang; Arun Bansil; Fangcheng Chou; Pavel P. Shibayev; Hsin Lin; Shuang Jia; M. Zahid HasanScience 349(6248), p.613-617A Weyl semimetal is a new state of matter that hosts Weyl fermions as emergent quasiparticles and admits a topological classification that protects Fermi arc surface states on the boundary of a bulk sample. This unusual electronic structure has deep analogies with particle physics and leads to unique topological properties. We report the experimental discovery of a Weyl semimetal, tantalum arsenide (TaAs). Using photoemission spectroscopy, we directly observe Fermi arcs on the surface, as well as the Weyl fermion cones and Weyl nodes
83 105/1 物理系 李啟正 助理教授 期刊論文 發佈 Absolute Binding Energies of Core levels in Solids from First Principles , [105-1] :Absolute Binding Energies of Core levels in Solids from First Principles期刊論文Absolute Binding Energies of Core levels in Solids from First PrinciplesTaisuke Ozaki; Chi-Cheng LeePhys. Rev. Lett. 118(2), 026401A general method is presented to calculate absolute binding energies of core levels in metals and insulators, based on a penalty functional and an exact Coulomb cutoff method in the framework of density functional theory. The spurious interaction of core holes between supercells is avoided by the exact Coulomb cutoff method, while the variational penalty functional enables us to treat multiple splittings due to chemical shift, spin-orbit coupling, and exchange interaction on equal footing, both of which are not accessible by previous methods. It is demonstrated that the absolute binding energies of core levels for both metals and insulators are calculated by the proposed method in a mean absolute (relative) error of 0.4 eV (0.16%) for eight cases compared to experimental values meas
84 98/1 物理系 李啟正 助理教授 期刊論文 發佈 Ferro-Orbital Order and Strong Magnetic Anisotropy in the Parent Compounds of Iron-Pnictide Superconductors , [98-1] :Ferro-Orbital Order and Strong Magnetic Anisotropy in the Parent Compounds of Iron-Pnictide Superconductors期刊論文Ferro-Orbital Order and Strong Magnetic Anisotropy in the Parent Compounds of Iron-Pnictide SuperconductorsChi-Cheng Lee; Wei-Guo Yin; Wei KuPhys. Rev. Lett. 103(26), p.267001The puzzling nature of magnetic and lattice phase transitions of iron pnictides is investigated via a first-principles Wannier function analysis of representative parent compound LaOFeAs. A rare ferro-orbital ordering is found to give rise to the recently observed highly anisotropic magnetic coupling, and drive both phase transitions—without resorting to widely employed frustration or nesting picture. The revealed necessity of the additional orbital physics leads to a correlated electronic structure fundamentally distinct from that of the cuprates. In particular, the strong coupling to the magnons advocates active roles of light orbitons in spin dynamics and electron pairing in iron pnictides.en_US國外SCI@@
85 99/1 物理系 李啟正 助理教授 期刊論文 發佈 Dynamical Linear Response of TDDFT with LDA+U Functional: strongly hybridized Frenkel excitons in NiO , [99-1] :Dynamical Linear Response of TDDFT with LDA+U Functional: strongly hybridized Frenkel excitons in NiO期刊論文Dynamical Linear Response of TDDFT with LDA+U Functional: strongly hybridized Frenkel excitons in NiOChi-Cheng Lee; H. C. Hsueh; Wei KuPhys. Rev. B 82(8), 081106(R)Within the framework of time-dependent density-functional theory (TDDFT), we derive the dynamical linear response of local-density approximation plus U functional and benchmark it on NiO, a prototypical Mott insulator. Formulated using real-space Wannier functions, our computationally inexpensive framework gives detailed insights into the formation of tightly bound Frenkel excitons with reasonable accuracy. Specifically, a strong hybridization of multiple excitons is found to significantly modify the exciton properties. Furthermore, our study exposes a significant generic limitation of adiabatic approximation in TDDFT with hybrid functionals and in existing Bethe-Salpeter-equation approaches, advocating the necessity
86 102/1 物理系 李啟正 助理教授 期刊論文 發佈 Unfolding method for first-principles LCAO electronic structure calculations , [102-1] :Unfolding method for first-principles LCAO electronic structure calculations期刊論文Unfolding method for first-principles LCAO electronic structure calculationsChi-Cheng Lee; Yukiko Yamada-Takamura; Taisuke OzakiJ. Phys.: Condens. Matter 25(34), p.345501Unfolding the band structure of a supercell to a normal cell enables us to investigate how symmetry breakers such as surfaces and impurities perturb the band structure of the normal cell. We generalize the unfolding method, originally developed based on Wannier functions, to the linear combination of atomic orbitals (LCAO) method, and present a general formula to calculate the unfolded spectral weight. The LCAO basis set is ideal for the unfolding method because the basis functions allocated to each atomic species are invariant regardless of the existence of surface and impurity. The unfolded spectral weight is well defined by the property of the LCAO basis functions. In exchange for the property, the non-orthogonality of the LCAO basis fun
87 102/1 物理系 李啟正 助理教授 期刊論文 發佈 First-principles study on competing phases of silicene: Effect of substrate and strain , [102-1] :First-principles study on competing phases of silicene: Effect of substrate and strain期刊論文First-principles study on competing phases of silicene: Effect of substrate and strainChi-Cheng Lee; Antoine Fleurence; Rainer Friedlein; Yukiko Yamada-Takamura; Taisuke OzakiPhys. Rev. B 88(16), p.165404The stability and electronic structure of competing silicene phases under in-plane compressive stress, either free-standing or on the ZrB 2 (0001) surface, has been studied by first-principles calculations. A particular ( √ 3 × √ 3 )-reconstructed structural modification was found to be stable on the ZrB 2 (0001) surface under epitaxial conditions. In contrast to the planar and buckled forms of free-standing silicene, in this “planar-like” phase, all but one of the Si atoms per hexagon reside in a single plane. While without substrate, for a wide range of strain, this phase is energetically less favorable than the buckled one, it is calculated to represent the ground state on the ZrB 2
88 102/1 物理系 李啟正 助理教授 期刊論文 發佈 First-Principles Method of Propagation of Tightly Bound Excitons: Verifying the Exciton Band Structure of LiF with Inelastic x-Ray Scattering , [102-1] :First-Principles Method of Propagation of Tightly Bound Excitons: Verifying the Exciton Band Structure of LiF with Inelastic x-Ray Scattering期刊論文First-Principles Method of Propagation of Tightly Bound Excitons: Verifying the Exciton Band Structure of LiF with Inelastic x-Ray ScatteringChi-Cheng Lee, Xiaoqian M. Chen, Yu Gan, Chen-Lin Yeh, H. C. Hsueh, Peter Abbamonte, and Wei KuPhys. Rev. Lett. 111(15), p.157401We propose a simple first-principles method to describe the propagation of tightly bound excitons. By viewing the exciton as a composite object (an effective Frenkel exciton in Wannier orbitals), we define an exciton kinetic kernel to encapsulate the exciton propagation and decay for all binding energies. Applied to prototypical LiF, our approach produces three exciton bands, which we verified quantitatively via inelastic x-ray scattering. The proposed real-space picture is computationally inexpensive and thus enables study of the full exciton dynamics, even in the presence of s
89 102/2 物理系 李啟正 助理教授 期刊論文 發佈 Competing magnetism in π-electrons in graphene with a single carbon vacancy , [102-2] :Competing magnetism in π-electrons in graphene with a single carbon vacancy期刊論文Competing magnetism in π-electrons in graphene with a single carbon vacancyChi-Cheng Lee; Yukiko Yamada-Takamura; Taisuke OzakiPhys. Rev. B 90(1), p.014401One intriguing finding in graphene is the vacancy-induced magnetism that highlights the interesting interaction between local magnetic moments and conduction electrons. Within density functional theory, the current understanding of the ground state is that a Stoner instability gives rise to ferromagnetism of π-electrons aligned with the localized moment of a σ dangling bond and the induced π magnetic moments vanish at low vacancy concentrations. However, the observed Kondo effect suggests that π-electrons around the vacancy should antiferromagnetically couple to the local moment and should carry nonvanishing moments. Here we propose that a phase possessing both significant out-of-plane displacements and π bands with antiferromagnetic coupling to the locali
90 103/1 物理系 李啟正 助理教授 期刊論文 發佈 Band structure of silicene on zirconium diboride (0001) thin-film surface: Convergence of experiment and calculations in the one-Si-atom Brillouin zone , [103-1] :Band structure of silicene on zirconium diboride (0001) thin-film surface: Convergence of experiment and calculations in the one-Si-atom Brillouin zone期刊論文Band structure of silicene on zirconium diboride (0001) thin-film surface: Convergence of experiment and calculations in the one-Si-atom Brillouin zoneChi-Cheng Lee; Antoine Fleurence; Yukiko Yamada-Takamura; Taisuke Ozaki; Rainer FriedleinPhys. Rev. B 90(7), p.075422So far, it represents a challenging task to reproduce angle-resolved photoelectron (ARPES) spectra of epitaxial silicene by first-principles calculations. Here, we report on the resolution of the previously controversial issue related to the structural configuration of silicene on the Zr B2(0001) surface and its band structure. In particular, by representing the band structure in a large Brillouin zone associated with a single Si atom, it is found that the imaginary part of the one-particle Green's function follows the spectral weight observed in ARPES spectra. By additi
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