Yanhao Dong, I-Wei Chen, Ju Li
Oxygen ion migration in Li2MnO3 was systematically studied by first-principles calculations. Hole polaron is found effective to lower the migration barrier of oxygen ion.
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Influence of Zeeman splitting and thermally excited polaron states on magneto-electrical and magneto-thermal properties of magnetoresistive polycrystalline manganite La_{0.8}Sr_{0.2}MnO_3
磁阻锰氧化物的自旋和电荷自由度之间的一些可能的连接进行了研究，通过彻底的实验研究的磁性（交流磁化率和直流磁化）和运输（电阻率和热导率）的属性。测量报告的情况下，以及表征多晶La_{0.8} Sr_{0.2} MnO_3样品。实验结果表明，相当强的场致极化效应在我们的材料，清楚地表明有序FM区域内的半导体相的存在。使用适合自发DC磁化的分析表达式，发现电阻率和热导率数据的温度和磁场依赖性通过基于两种机制的通用方案被很好地再现：（i）受塞曼分裂效应影响的依赖于磁化强度的自旋极化子跳跃，以及（ii）为了正确描述导电性较低区域的行为而必须考虑的适当定义的热激发极化子状态。利用实验测得的磁和电子局域化温度，我们分别得到了局域化长度（自旋极化子的尺寸）和有效极化子质量的估计值L=0.5nm和m_p=3.2m_e。
Polaron and Strain Effects on Ion Migration in WO$_3$
本研究基于密度泛函理论探讨单斜WO$_3$中H$^+$、Li$^+$、Mg$^{2+}$的迁移机制，揭示极化子通过缔合效应和晶格变形增加能垒、晶格应变对不同离子迁移能垒影响各异的规律，为优化WO$_3$器件性能提供关键见解。
Doping Dependence of Polaron Hopping Energies in La(1-x)Ca(x)MnO(3) (0<= x<= 0.15)
测量了La（1-x）Ca（x）MnO（3）（0 ≤ x ≤ 0.15）在T ≤ 160 K时的低频（f ≤ 100 kHz）介电常数和T ≤ 430 K时的直流电阻率。静态介电常数由介电常数的低T极限行为确定。束缚空穴的极化率估计值约为10^{-22} cm^{-3}，这意味着其半径与原子间间距相当，这与之前在室温附近及更高温度下对附近成分的输运研究中建立的小极化子图像一致。弛豫峰的介电损耗与电荷载流子跳跃产生的活化能与低T跳跃能量确定的直流电阻率的可变范围跳跃拟合的良好协议。这些能量的掺杂依赖性表明，斜方晶系，倾斜的反铁磁基态倾向于绝缘体-金属过渡，这是由于在Mn（4+）浓度约0.13附近形成铁磁绝缘态而未实现的。
Hole polaron formation and migration in olivine phosphate materials
通过结合第一性原理计算和实验XPS测量，研究了潜在的锂离子电池正极材料LiMPO 4（M=Mn，Fe，Co，Ni）的电子结构，揭示了决定小孔极化子形成和迁移的潜在机制.我们表明，小孔极化子的形成取决于附近的价带最大值的电子结构的功能，计算上，这些功能取决于所选择的方法来处理的过渡金属d-衍生状态在这些系统中的相关性质。与实验结果的比较表明，混合泛函方法在正确再现XPS谱方面优于GGA+U。使用这种方法，我们发现LiNiPO 4不能支持小空穴极化子，但其他三种化合物可以。迁移势垒主要由价带顶部的状态的强或弱键合性质决定，导致LiMnPO 4的势垒比LiCoPO 4或LiFePO 4高得多。
Migration volume for polaron dielectric relaxation in disordered materials
从理论上研究了压力对无序固体中与极化子隧穿和声子助跳有关的介电弛豫的影响。的符号和绝对值的迁移量，这是通过采用本配方，证据的性质的放松。作为一个范例，迁移体积的正值和负值进行评估，通过分析最近发表的半导体聚吡咯的压力下的介电损耗测量。迁移量的值和短程极化子流的性质和极化子畸变的大小之间的直接关系被揭示。
The understanding of the Physics underlying the performances of organic spin-valve devices is still incomplete. According to some recent models, spin transport takes place in an impurity band inside the fundamental gap of organic semiconductors. This seems to be confirmed by recent experiments performed with La$_{0.7}$Sr$_{0.3}$MnO$_3$/Alq$_3$/AlO$_x$/Co devices. The reported results suggest a possible correlation between the magnetoresistance and the variable oxygen doping in the Alq$_3$ spacer. In this paper we investigate by means of first-principles calculations the electronic and magnetic…
Grotthuss-type oxygen hole polaron transport in desodiated Na$_{2}$Mn$_3$O$_7$
本研究在脱钠Na₂Mn₃O₇中发现罕见分裂氧空穴极化子，通过DFT揭示其沿b轴的类Grotthuss分步迁移机制，计算了迁移率等参数，为奇异极化子输运及功能材料研发提供新理论见解。
Migration of photogenerated charge carriers in silver halides: small polaron transport
近半个世纪前，我参加了一个雄心勃勃的研究项目，旨在建立离子盐的光分解机制。我们测量了溴化银中光电子和光空穴的迁移率和寿命，以获得该过程的早期知识。最后一对要研究的量是我们得到结果的扩散系数，这在当时是非常有争议的。现在，我们表明，扩散数据表明形成巡回扬泰勒小极化子作为下一阶段的光载流子在卤化银。
First-principles study on Small Polaron and Li diffusion in layered LiCoO2
本文通过第一性原理研究层状LiCoO2中极化子对锂扩散的影响，发现磁有序下Co4+极化子虽提高扩散势垒但使迁移更稳定，从而提出空穴极化子迁移机制。
Polaron Conductivity in $α$-Fe2O3 Quenched by Adsorbed NO2
研究通过DFT+U和 nudged elastic band计算，揭示了α-Fe₂O₃表面极化子形成与淬灭机制，发现NO₂吸附导致电子转移，抑制极化子导电性，为铁氧化物气体传感器设计提供新原理。
Acceptor-doped perovskite oxides like BaZrO$_3$ are showing great potential as materials for renewable energy technologies where hydrogen acts an energy carrier, such as solid oxide fuel cells and hydrogen separation membranes. While ionic transport in these materials has been investigated intensively, the electronic counterpart has received much less attention and further exploration in this field is required. Here, we use density functional theory (DFT) to study hole polarons and their impact on hole conductivity in Y-doped BaZrO$_3$. Three different approaches have been used to remedy the s…
Revealing Short- and Long-range Li-ion diffusion in Li$_2$MnO$_3$ from finite-temperature dynamical mean field theory
结合DFT+$U$、有限温度DFT+DMFT和NEB方法，研究顺磁Li$_2$MnO$_3$中单个锂空位存在下的Li$^{+}$迁移，发现动力学关联显著重整最低势垒过程，短程跳跃活化能0.18 eV与μ$^{+}$SR一致，长程输运活化能0.50 eV与交流阻抗测量吻合，无需引入团簇空位或强无序即可统一解释局域和宏观探针。
Uncovering coupled ionic-polaronic dynamics and interfacial enhancement in Li$_x$FePO$_4$
本研究开发微调机器学习力场，揭示LiFePO4中极化子翻转远快于锂迁移，并在相界增强，为多价电池正极耦合输运提供新见解。
Electrical-transport characteristics of as-grown and oxygen-reduced La$_{0.7}$Ce$_{0.3}$MnO$_3$ films: calculation of hopping energies, Mn valences, and carrier localization lengths
目前，铈掺杂的LaMnO $_3$被生动地讨论为电子掺杂的对应原型，以充分建立的空穴掺杂的混合价锰氧化物。在此，比较在SrTiO $_3$单晶衬底上生长的不同厚度、CeO $_3$相分离程度和氧缺乏的La $_{0.7}$ Ce $_{0.3}$ MnO $_3$薄膜的电阻-相对电阻-相对电阻。从300~ 90 K的温度（R vs. T）行为。当薄膜厚度在10~ 100 nm范围内变化时，外延应变对电输运的影响很小，而CeO $_2$团簇的存在和氧的缺乏则完全改变了跳跃机制的类型.这是通过拟合各自的\textit{R-T}曲线与三种不同的传输模型（绝热极化子跳跃，莫特可变范围跳跃，埃夫罗斯-什克洛夫斯基可变范围跳跃），这是常用的混合价锰氧化物。几个特征的输运参数，如跳跃能量，载流子局域化长度，以及Mn价从拟合程序推导出来。
First-principles investigation of small polarons in rhombohedral NaNbO$_{3}$
本研究通过从头原理计算探讨了 rhombohedral NaNbO$_{3}$ 中小空穴和电子极子的稳定性，发现氧是 NaNbO$_{3}$ 内在的空穴陷阱，并强调了在 NaNbO$_{3}$ 基电陶瓷的缺陷模型中包括空穴极子的重要性。
We report on high-dimensional quantum dynamical simulations of torsion-induced exciton migration in a single-chain oligothiophene segment comprising twenty repeat units, using a first-principles parametrized Frenkel J-aggregate Hamiltonian. Starting from an initial inter-ring torsional defect, these simulations provide evidence of an ultrafast two-time scale process at low temperatures, involving exciton-polaron formation within tens of femtoseconds, followed by torsional relaxation on a ~300 femtosecond time scale. The second step is the driving force for exciton migration, as initial conjuga…
Multivalent batteries are an energy storage technology with the potential to surpass lithium-ion batteries, however their performance has been limited by the low voltages and poor solid-state ionic mobility of available cathodes. A computational screening approach to identify high-performance multivalent intercalation cathodes among materials that do not contain the working ion of interest has been developed which greatly expands the search space that can be considered for materials discovery. This approach has been applied to magnesium cathodes as a proof of concept and four resulting candida…
First principles modeling of oxygen adsorption on LaMnO3 (001) surface
我们提出并讨论了原子和分子氧在固体氧化物燃料电池阴极模型材料LaMnO 3（001）表面的吸附和扩散的从头算DFT平面波超原电池计算结果。从气相中的O2分子的解离吸附是积极有利的表面Mn离子，即使在无缺陷的表面上。吸附的O离子的表面迁移能被发现是相当高的，1.6 eV。我们预测，吸附的O原子可以渗透到电极的第一平面时，更多的移动表面氧空位（迁移能为0.69 eV）的方法，O离子强烈结合到表面Mn离子。从头算热力学预测，在典型的SOFC工作温度（~1200 K）下，吸附有氧原子的MnO 2（001）表面在很宽的氧气压力范围内（高于10^2 atm）是最稳定的。
As a prototypical Mott insulator with ferromagnetic ordering, YTiO3 (YTO) is of great interest in the study of strong electron correlation effects and orbital ordering. Here we report the first molecular beam epitaxy (MBE) growth of YTO films, combined with theoretical and experimental characterization of the electronic structure and charge transport properties. The obstacles of YTO MBE growth are discussed and potential routes to overcome them are proposed. DC transport and Seebeck measurements on thin films and bulk single crystals identify p-type Arrhenius transport behavior, with an activa…
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