首 页
滚动信息 更多 >>
本刊2021年SCI影响因子12.256 (2022-07-07)
npj Computational Materials 2019年影响因子达到9... (2020-07-04)
npj Computational Materials获得第一个SCI影响因... (2018-09-07)
英文刊《npj Computational Materials(计算材料学... (2017-05-15)
开放的数据库 (2015-12-17)
快捷服务
最新文章 研究综述
过刊浏览 作者须知
期刊编辑 审稿须知
相关链接
· 在线投稿
会议信息
友情链接
  中国科学院上海硅酸盐研究所
  无机材料学报
  OQMD数据库
mm.jpg
期刊介绍

  《npj 计算材料学》是在线出版、完全开放获取的国际学术期刊。发表结合计算模拟与设计的材料学一流的研究成果。本刊由中国科学院上海硅酸盐研究所与英国自然出版集团(Nature Publishing Group,NPG)以伙伴关系合作出版。
  主编为陈龙庆博士,美国宾州大学材料科学与工程系、工程科学与力学系、数学系的杰出教授。共同主编为陈立东研究员,中国科学院上海硅酸盐研究所研究员高性能陶瓷与超微结构国家重点实验室主任。
  办刊目的与报道范围
  《npj 计算材料学》是在线出版、完全开放获取的国际学术...
【查看详细】
近期文章 更多 >>

Delocalization of dark and bright excitons in flat-band materials and the optical properties of V2O5        
Vitaly Gorelov, Lucia Reining, Martin Feneberg, Rüdiger Goldhahn, André Schleife, Walter R. L. Lambrecht  & Matteo Gatti       
npj Computational Materials 8: 94 (2022)
doi.org/10.1038/s41524-022-00754-2
Published online: 28 April 2022
Abstract| Full Text | PDF OPEN

Abstract: The simplest picture of excitons in materials with atomic-like localization of electrons is that of Frenkel excitons, where electrons and holes stay close together, which is associated with a large binding energy. Here, using the example of the layered oxide V2O5, we show how localized charge-transfer excitations combine to form excitons that also have a huge binding energy but, at the same time, a large electron-hole distance, and we explain this seemingly contradictory finding. The anisotropy of the exciton delocalization is determined by the local anisotropy of the structure, whereas the exciton extends orthogonally to the chains formed by the crystal structure. Moreover, we show that the bright exciton goes together with a dark exciton of even larger binding energy and more pronounced anisotropy. These findings are obtained by combining first principles many-body perturbation theory calculations, ellipsometry experiments, and tight binding modeling, leading to very good agreement and a consistent picture. Our explanation is general and can be extended to other materials.

摘要: 在具有类原子局域电子的材料中,激子最简单的图像是Frenkel激子,其中电子和空穴紧密靠着,这与大的结合能有关。在这里,以层状氧化物V2O5为例,我们展示了局域电荷转移激发是如何结合形成激子的,这些激子具有巨大的结合能,但电子-空穴的距离同时也很大,我们解释了这个看似矛盾的发现。激子离域的各向异性是由结构的局部各向异性决定的,而激子则正交地延伸到由晶体结构形成的链上。此外,我们发现明亮的激子是与一个具有更大结合能和更明显各向异性的暗激子一起出现的。这些发现通过结合第一性原理多体微扰理论计算、椭圆偏振实验和紧密结合模型得到,取得了非常好的一致性图像。我们的解释具有普适性且可以推广到其他材料。

Editorial Summary

Intriguing bright and dark excitons inV2O5

It is common belief that the exciton binding energy is directly dependent on spatial localization. The classical Wannier and Frenkel textbook models describe, respectively, the limiting cases of weakly bound and delocalized excitons, typically found in ordinary semiconductors, and tightly bound and localized excitons, observed in molecular or noble gas solids. Recent development of two-dimensional (2D) materials have sparked the interest in exploring excitons that stand out from the conventional expectation. 2D materials usually have large exciton binding energies, irrespective of spatial extent, which can be rationalized as the consequence of reduced effective screening. However, there has been a long-standing controversy about whether strongly bound charge-transfer excitons can be considered Frenkel excitons. This work proposes an exciton model that explains the counter-intuitive anisotropy and delocalization of charge-transfer excitons. Prof. Gorelov and coworkers from Institut Polytechnique de Paris and coworkers, take V2O5 as a prototypical system to study how the localized charge-transfer excitations form an exciton by combing first-principles calculations, ellipsometry experiments and tight-binding model. As a flat-band material, V2O5 has intriguing excitons which contradict textbook expectations. Flat bands correspond to localized electronic states, and the exciton binding energy is very large. When the single-particle excitations that are mixed to form an exciton are charge-transfer excitations, the wave function of the exciton is delocalized, which shows an anisotropy determined by the local motif of the charge-transfer unit. In addition, they found that the dark and bright excitons are strongly bound in the gap. In the lowest dark and bright excitons, the electron density for a hole on a bridge oxygen extends perpendicular to the atomic chains along which electrons disperse. This work provides valuable guidelines for identifying materials where excitons exhibit properties tailored for specific needs.

编辑概述

V2O5材料中奇特的明暗激子

激子的结合能通常被认为与其空间位置有关。教科书上经典的 Wannier 和 Frenkel 模型分别描述了通常在普通半导体中观察到的弱束缚(离域)激子和在分子或惰性气体中观察到的紧密束缚(局域)激子的极限情况。近年来二维材料的发展,引起了人们探索与传统激子特性不一样的激子系统。二维材料的激子结合能普遍很大,且与与空间位置无关,这通常被认为与低维材料的有效屏蔽有关。然而,关于是否可以将强束缚电荷转移激子认为是 Frenkel 激子还一直存在争议。本工作中提出了一个激子模型,成功解释了电荷转移激子的各向异性和离域性质。来自法国巴黎理工学院的Gorelov教授及其同事,以V2O5作为研究原型对象,结合第一性原理计算、椭偏实验和紧束缚模型,研究了局部电荷转移激发是如何形成激子的。V2O5作为平带材料,其激子具有与传统预期相矛盾的有趣特性:平带对应于局部电子态,激子结合能非常大。当混合形成激子的单粒子激发具有镜像对称性的电荷转移激发时,激子的波函数是离域的,并显示出了由电荷转移单元局部基序控制的各向异性。此外,他们还发现,明暗激子是一起出现在间隙中的,他们强烈的束缚在一起。在最低的明暗激子中,V2O5中桥氧上的空穴电子密度垂直于电子分散的原子链。这项工作为识别具有特定需求的激子的材料提供了有价值的指导。

Atomic coordination dictates vibrational characteristics and thermal conductivity in amorphous carbon        
Ashutosh Giri, Connor J. Dionne & Patrick E. Hopkins      
npj Computational Materials 8: 55 (2022)
doi.org/10.1038/s41524-022-00741-7
Published online: 4 April 2022
Abstract| Full Text | PDF OPEN

Abstract: We discuss the role of atomic coordination in dictating the vibrational characteristics and thermal conductivity in amorphous carbon. Our systematic atomistic simulations on amorphous carbon structures at varying mass densities show the significant role played by the ratio of sp2 to sp3 hybridized bonds in dictating the contributions from propagating (phonon-like) and non-propagating vibrational modes and their influence on the overall thermal conductivities of the structures. Specifically, our results show that as the concentration of sp3-bonded carbon atoms increases, the thermal conductivity can be increased by four fold, which is attributed to enhanced contributions from propagating modes in these amorphous structures. Our results shed more light into the role of atomic coordination on dictating heat transfer mechanisms in amorphous materials, and also provide a deeper understanding of the ability to tune the thermal conductivity of amorphous carbon structures through the control of the local atomic coordination.

摘要: 我们讨论了原子配位在决定非晶碳的振动特性和热导率中的作用。我们对不同质量密度的非晶碳结构进行了系统原子模拟,结果表明,sp2 与 sp3 杂化键的比率在决定传播(类声子)和非传播振动模式的贡献,及其对结构整体热传导的影响方面发挥了重要作用。具体来说,我们的结果表明,随着 sp3 键合碳原子浓度的增加,热导率可以增加四倍,这可归因于这些非晶结构中传播模式的贡献增强。我们的研究结果进一步阐明了原子配位在决定非晶材料传热机制中的角色,并提供了对通过控制局部原子配位来调节非晶碳结构热导率能力的更深入理解。

Editorial Summary

Thermal conductivity in amorphous carbon: atomic coordination

Diamond-like carbon is a class of amorphous carbon material that has attracted much attention over more than half a century due to its unique combination of properties that are tunable between those found in diamond and those in graphite. Depending on the sp3 content in amorphous carbon, the chemical and physical properties can be controlled over a wide range. In particular, there has been a considerable amount of interest in understanding thermal transport properties in amorphous carbon both from experimental and computational standpoints. Up to now, however, a systematic study focusing on the influence of relative fractions of sp3- and sp2-bonded carbons on the thermal transport properties of amorphous carbon structures is still missing. Moreover, it is also not clear what impact carbon hybridization has on the fundamental character of the different vibrational modes in amorphous carbon. This study discusses the role of atomic coordination in dictating the vibrational characteristics and thermal conductivity in amorphous carbon. A team led by Prof. Patrick E. Hopkins from University of Virginia, USA, has studied the role of carbon hybridization on the vibrational heat transfer mechanisms in amorphous carbon structures via systematic atomistic simulations. The results show the significant role played by the fraction of sp3-bonded carbon atoms in dictating the contributions from propagating (phonon-like) vibrational modes and their influence on the overall thermal conductivity. The study shows that as the concentration of sp3-bonded carbon atoms increases from ~10 to ~80% in our amorphous carbon structures, the thermal conductivity can be increased by four folds, which is due to the drastic increase in the contribution from propagating modes. For the amorphous carbon structure with the highest concentration of sp3-bonded carbon, the thermal conductivity can reach a record high value of 11?W?m?1?K?1, which is the highest thermal conductivity for any known amorphous solid till date. This study reveals the relationship between atomic coordination and the fundamental characteristics of the vibrational modes in amorphous carbon, thus opening an avenue to efficiently tune the thermal conductivity of these materials based on carbon hybridization. 

编辑概述

非晶碳热导率:原子配位

类金刚石碳在半个多世纪以来一直备受关注。它是一种非晶碳材料,具有在金刚石和石墨之间可调节的独特性能。根据非晶碳中的sp3含量,可以在很宽的范围内控制其化学和物理特性。特别是针对非晶碳的热传输特性,人们一直有着极大的兴趣,也得到实验和理论方面的长期研究。然而,针对sp3与sp2键合碳的比率对非晶碳结构的热传输性质影响的系统研究至今缺乏。此外,碳杂化对非晶碳中不同振动模式的基本特征的影响仍不清楚。该研究讨论了原子配位在决定非晶碳的振动特性和热导率中的作用。来自美国弗吉尼亚大学的Patrick E. Hopkins教授领导的团队,通过系统的原子模拟,研究了碳杂化对非晶碳结构中振动传热机制的作用。该研究结果表明,sp3键合碳原子的比例在决定传播(类声子)振动模式的贡献及其对整体热导率的影响方面发挥了重要作用。研究发现,随着非晶碳结构中sp3键合碳原子的浓度从~10%增加到~80%,传播模式的贡献急剧增加,从而使热导率可以增加四倍。对于具有最高浓度sp3键合碳的非晶碳结构,其热导率可以达到创纪录的11?W?m?1?K?1,这是迄今为止已知非晶固体的最高热导率。该研究揭示了原子配位与非晶碳中振动模式的基本特征之间的关系,为基于碳杂化有效调节这些材料的热导率开辟了一条途径。

Dilute carbon in H3S under pressure        
Xiaoyu Wang, Tiange Bi, Katerina P. Hilleke, Anmol Lamichhane, Russell J. Hemley & Eva Zurek     
npj Computational Materials 8: 87 (2022)
doi.org/10.1038/s41524-022-00769-9
Published online: 27 April 2022
Abstract| Full Text | PDF OPEN

Abstract: Recently, room temperature superconductivity was measured in a carbonaceous sulfur hydride material whose identity remains unknown. Herein, first-principles calculations are performed to provide a chemical basis for structural candidates derived by doping H3S with low levels of carbon. Pressure stabilizes unusual bonding configurations about the carbon atoms, which can be six-fold coordinated as CH6 entities within the cubic H3S framework, or four-fold coordinated as methane intercalated into the H-S lattice, with or without an additional hydrogen in the framework. The doping breaks degenerate bands, lowering the density of states at the Fermi level (NF), and localizing electrons in C-H bonds. Low levels of CH4 doping do not increase NF to values as high as those calculated for Im3(_)m-H3S, but they can yield a larger logarithmic average phonon frequency, and an electron–phonon coupling parameter comparable to that of R3m-H3S. The implications of carbon doping on the superconducting properties are discussed.

摘要: 最近,研究人员测得了一种具有室温超导性的碳质硫氢化物材料,但其本征结构还未知。在这里,我们通过第一性原理计算,为低碳掺杂 H3S 衍生的结构候选物提供了化学基础。压力稳定了碳原子周围反常的键合构型,在框架中有或没有额外的氢的情况下,碳原子可以作为立方 H3S 框架内的 CH6形成六倍配位,或者作为甲烷插入 H-S 晶格中形成四倍配位。掺杂打破了简并能带,降低了费米能级 (NF)处的态密度,并将电子局域在 C-H 键中。低浓度 CH4 掺杂不会将 NF 增加到与 Im3(_)m-H3S计算值一样高的值,但它们可以产生更大的对数平均声子频率,并产生与 R3m-H3S 相当得电子 - 声子耦合参数。本文讨论了碳掺杂对超导特性的影响。

Editorial Summary

Superconducting phase of low-level C doped H3S: First-principles exploration

During the past decades, tremendous efforts have been made in the exploration of room temperature superconductors, and fruitful results have been obtained. Earlier studies predicted that hydrogen-rich compounds metallized under pressure could be phonon-mediated high-temperature superconductors, where synergy between experiment and theory has led to remarkable progress. One typical example is H3S, for which a superconducting critical temperature, Tc, of 203?K was reported near 150?GPa; Another example is carbonaceous sulfur hydride superconductor, which has a Tc of 288?K at 267?GPa. So far, a critical issue lies in the composition and structure of the phase, or phases that are responsible for the remarkable superconductivity. This aims to provide a chemical basis for structural candidates derived by doping H3S with low levels of carbon. A team led by Professor Eva Zurek from the Departments of Physics, Chemistry, and Earth and Environmental Sciences, University of Illinois Chicago and Professor Russell J. Hemley from the Department of Chemistry, State University of New York at Buffalo, explored the effects of carbon doping on the structural, electronic and superconducting properties of H3S. They systematically investigated the doping of H3S by 1.85–25% carbon that leads to a plethora of metastable phases, associated with the thermal and dynamic properties. They considered different types of substitution, including S being replaced by C, plus different amounts of hydrogen, where carbon can be either six-coordinated or four-coordinated to hydrogen. It was found that CH6 and CH4 form stable configurations within the dense solid in phases that are dynamically stable at the pressures studied experimentally. The doping breaks degenerate bands, lowers the density of states at the Fermi level and localizes electrons in C-H bonds, which affect the superconducting properties. 

编辑概述

低碳掺杂H3S的超导相:第一性原理探寻

室温超导体在过去几十年里得到广泛研究,同时也取得到不少成果。前期,人们预测在压力下金属化的富氢化合物可能是声子介导的高温超导体,之后实验与理论也取得了协同发展。其中一个典型的材料是H3S,其超导临界温度Tc在150?Gpa时达到203?K;后来,人们又报道了一种在267?GPa时Tc为 288?K 的碳质硫氢化物超导体。迄今一个关键问题是,导致碳质H3S超导性的相组成和结构犹未可知。来自伊利诺伊大学芝加哥分校物理、化学、地球与环境科学系的Eva Zurek与纽约州立大学布法罗分校化学系的Russell J. Hemley等,通过第一性原理计算,为低碳掺杂 H3S 衍生的结构候选物提供了化学基础。他们研究了碳掺杂对H3S几何、电子结构和超导性能的影响。该研究系统地计算1.85–25%碳掺杂H3S系统的各种亚稳定结构,热力学和动力学稳定性。作者考虑了S被C原子取代的不同类型结构,加上不同数量的氢,生成六配位或四配位碳原子。研究发现,在实验研究的压力下,CH6和CH4在致密固体中可以形成稳定的构型。此外,掺杂降低了费米能处的态密度,破坏了简并度并使电子在碳氢键中局域化,这对超导特性有重要影响。

XGBoost model for electrocaloric temperature change prediction in ceramics        
Jie Gong, Sharon Chu, Rohan K. Mehta & Alan J. H. McGaughey    
npj Computational Materials 8: 140 (2022)
doi.org/10.1038/s41524-022-00826-3
Published online: 1 July 2022
Abstract| Full Text | PDF OPEN

Abstract: An eXtreme Gradient Boosting (XGBoost) machine learning model is built to predict the electrocaloric (EC) temperature change of a ceramic based on its composition (encoded by Magpie elemental properties), dielectric constant, Curie temperature, and characterization conditions. A dataset of 97 EC ceramics is assembled from the experimental literature. By sampling data from clusters in the feature space, the model can achieve a coefficient of determination of 0.77 and a root mean square error of 0.38?K for the test data. Feature analysis shows that the model captures known physics for effective EC materials. The Magpie features help the model to distinguish between materials, with the elemental electronegativities and ionic charges identified as key features. The model is applied to 66 ferroelectrics whose EC performance has not been characterized. Lead-free candidates with a predicted EC temperature change above 2?K at room temperature and 100?kV/cm are identified.

摘要: 建立了一个 eXtreme Gradient Boosting (XGBoost) 机器学习模型,用于根据陶瓷的成分(由 Magpie 元素特性编码)、介电常数、居里温度和表征条件来预测陶瓷的电卡 (EC) 温度变化。从实验文献中构筑了 97 个 EC 陶瓷的数据集。通过从特征空间中的簇中采样数据,该模型可以实现测试数据的决定系数为 0.77,均方根误差为 0.38?K。特征分析表明,该模型捕获了有效 EC 材料的已知物理特性。 Magpie 特征有助于模型区分材料,元素电负性和离子电荷被确定为关键特征。该模型应用于 66 种 EC 性能尚未表征的铁电体。确定了在室温下预测 EC 温度变化高于 2?K 和 100?kV/cm 的无铅候选物。

Editorial Summary

Difficulty to find electrocaloric ceramics? Machine learning will lead the way

The electrocaloric (EC) effect is the coupling temperature and entropy change of dielectric materials caused by the polarization change caused by the application or removal of the electric field. The EC cooling device may reach 60-70% of the Carnot coefficient of performance, which is more effective than the thermal electric device. Compared with the large magnetic field required by the magneto thermal cooling device, the large electric field required to operate the EC cooling device is easily generated. EC temperature change( Δ TEC) is a function of material, characterization temperature and applied electric field. Its size is usually large near the phase transition temperature and increases with the increase of the applied electric field. The key to construct EC cooling device is to find a large Δ TEC's materials. Identifying effective EC materials is a difficult task. In order to help find effective EC materials, the team of Professor Alan J. H. McGaughey from the Department of mechanical engineering of Carnegie Mellon University applied the data-driven method to build a machine learning (ML) model to predict the mechanical properties of ceramics according to the material composition, dielectric constant, Curie temperature and characterization conditions Δ TEC。 They established a limit gradient lifting (xgboost) model to predict the composition, dielectric constant, Curie temperature and characterization conditions of ceramic ferroelectric materials Δ TEC。 The data set was made up of available experiments Δ Tec measurements are combined. The model correctly identifies the known physical fields (i.e., the applied electric field and the difference between the characterization and Curie temperature) that cause large EC temperature changes. The model is applied to find effective EC materials from 66 kinds of ferroelectrics whose EC properties have not been characterized, and propose candidate materials for future experimental verification. The predictive power of the xgboost model indicates that the physics based data-driven approach is a promising way to study EC materials. 

编辑概述

电卡陶瓷找不到,机器学习来领道

电卡 (EC) 效应是施加或去除电场造成介电材料极化变化而引起的温度和熵的耦合变化,EC 冷却装置比热电装置更有效,有可能达到卡诺性能系数的 60%-70%。与磁热冷却装置所需的大磁场相比,运行 EC 冷却装置所需的大电场很容易产生。EC 温度变化 (ΔEC) 是材料、表征温度和外加电场的函数。它的大小通常在相变温度附近较大,并且随着施加的电场强度增加而增加。构建 EC 冷却装置的关键是找到具有较大ΔTEC的材料。但识别有效的 EC 材料是一项艰巨的任务。为了有效地寻找EC材料,来自美国卡内基梅隆大学机械工程系的Alan J. H. McGaughey教授团队,应用数据驱动的方法来构建机器学习(ML) 模型,以根据材料成分、介电常数、居里温度和表征条件来预测陶瓷的 ΔTEC。他们建立了一个极限梯度提升 (XGBoost) 模型,以根据陶瓷铁电材料的成分、介电常数、居里温度和表征条件来预测其 ΔTEC。该数据集由可用的实验 ΔTEC测量值组合而成,其模型正确识别了导致较大 EC 温度变化的已知物理场(即,施加的电场以及表征和居里温度之间的差异)。应用该模型从66 种 EC 性能尚未表征的铁电体中寻找有效的 EC 材料,并为未来的实验验证提出候选材料。XGBoost 模型的预测能力表明,基于物理的数据驱动方法是研究 EC 材料的有前途的路径。

Superconductivity in antiperovskites        
Noah Hoffmann, Tiago F. T. Cerqueira, Jonathan Schmidt & Miguel A. L. Marques    
npj Computational Materials 8: 150 (2022)
doi.org/10.1038/s41524-022-00817-4
Published online: 13 July 2022
Abstract| Full Text | PDF OPEN

Abstract: We present a comprehensive theoretical study of conventional superconductivity in cubic antiperovskites materials with composition XYZ3 where X and Z are metals, and Y is H, B, C, N, O, and P. Our starting point are electron–phonon calculations for 397 materials performed with density-functional perturbation theory. While 43% of the materials are dynamically unstable, we discovered 16 compounds close to thermodynamic stability and with Tc higher than 5?K. Using these results to train interpretable machine-learning models, leads us to predict a further 57 (thermodynamically unstable) materials with superconducting transition temperatures above 5?K, reaching a maximum of 17.8?K for PtHBe3. Furthermore, the models give us an understanding of the mechanism of superconductivity in antiperovskites. The combination of traditional approaches with interpretable machine learning turns out to be a very efficient methodology to study and systematize whole classes of materials and is easily extendable to other families of compounds or physical properties.

摘要: 我们对立方反钙钛矿材料的常规超导性进行了全面的理论研究,其成分为 XYZ3,其中 X 和 Z 是金属,Y 是 H、B、C、N、O 和 P。我们的出发点是对 397 种材料的电子-声子计算用密度泛函微扰理论进行。虽然 43% 的材料是动态不稳定的,但我们发现了 16 种接近热力学稳定性且 Tc 高于 5?K 的化合物。使用这些结果来训练可解释的机器学习模型,我们可以预测另外 57 种(热力学不稳定)材料超导转变温度高于 5?K,PtHBe3 最高可达 17.8?K。此外,这些模型让我们了解了反钙钛矿的超导机制。传统方法与可解释的机器学习相结合被证明是研究和系统化整个材料类别的一种非常有效的方法,并且很容易扩展到其他化合物或物理特性家族。

Editorial Summary

Power of Informatics: Performance Optimization of dye-sensitized solar cells

Perovskite is one of the widely studied ternary compounds and has been applied in many technical fields, such as photovoltaic, piezoelectric, magnetic, thermoelectric, laser, multiferroic and so on. One field where perovskite plays a key role is superconductivity. Copper oxide ceramics that maintain the highest transition temperature (TC) record belong to this family. In recent years, several other carbides, borides, even nitrides and oxide anti perovskite have been found to be superconductors, but their superconducting transformation mechanism is still controversial. Professor Miguel A. L. Marques, from Institut für Physik, Martin-Luther-Universit?t Halle-Wittenberg,, Germany, combined the standard method with the updated machine learning method to conduct a comprehensive theoretical study on the conventional superconductivity of cubic anti perovskite materials. It is not only to study the physical properties of a specific system, but also to understand the overall behavior of the entire compound family. Specifically, they used the density functional perturbation theory to calculate the electron phonon properties. For machine learning, the selected algorithm can not only predict the relevant physical properties (electron phonon coupling strength λ and average phonon frequency ω, But also can provide data interpretation. These models can clarify the superconducting mechanism of antiperovskite. The combination of traditional methods and interpretable machine learning has proved to be a very effective method for studying and systematizing the whole material class, and it is easy to extend to other compounds or physical property families. 

编辑概述

机器学习:反钙钛矿的超导机理研究

钙钛矿是被广泛研究的三元化合物家族之一,在许多技术领域都有应用,例如光伏、压电、磁性、热电、激光、多铁性等。钙钛矿具有关键作用的一个领域是超导性,保持最高转变温度(Tc)记录的铜氧化物陶瓷就属于这个家族。近年来发现其它几种碳化物、硼化物,甚至氮化物和氧化物反钙钛矿被实验证明是超导体,但是其超导转变机理还存在争议。来自德国马丁路德?哈勒维腾贝格大学物理研究所的Miguel A. L. Marques教授团队将标准方法与更新的机器学习方法结合使用,对立方反钙钛矿材料的常规超导性进行了全面的理论研究。不仅是研究特定系统的物理特性,而且是了解整个化合物家族的整体行为。具体来说,他们采用密度泛函微扰理论来计算电子 - 声子特性。对于机器学习,选择的算法不仅能够预测相关的物理特性(电子-声子耦合强度 λ 和平均声子频率 ω),而且还能够提供数据的解释。这些模型能够明确反钙钛矿的超导机制。传统方法与可解释的机器学习相结合被证明是研究和系统化整个材料类别的一种非常有效的方法,并且很容易扩展到其他化合物或物理特性家族。

Photovoltaphores: pharmacophore models for identifying metal-free dyes for dye-sensitized solar cells         
Hadar Binyamin & Hanoch Senderowitz    
npj Computational Materials 8: 142 (2022)
doi.org/10.1038/s41524-022-00823-6
Published online: 04 July 2022
Abstract| Full Text | PDF OPEN

Abstract: Dye-sensitized solar cells (DSSCs) are cost-effective, sustainable, and versatile electricity producers, allowing them to be incorporated into a variety of devices. In this work, we explore the usage of pharmacophore modeling to identify metal-free dyes for DSSCs by means of virtual screening. Pharmacophore models were built based on experimentally tested sensitizers. Virtual screening was performed against a large dataset of commercially available compounds taken from the ZINC15 library and identified multiple virtual hits. A subset of these hits was subjected to DFT and time-dependent-DFT calculations leading to the identification of two compounds, TSC6 and ASC5, with appropriate molecular orbitals energies, favorable localization, and reasonable absorption UV–vis spectra. These results suggest that pharmacophore models, traditionally used in drug discovery and lead optimization, successfully predicted electronic properties, which are in agreement with the theoretical requirements for sensitizers. Such models may therefore find additional usages as modeling tools in materials sciences.

摘要: 染料敏化太阳能电池 (DSSC) 是具有成本效益、可持续且用途广泛的电力供应单元,可以将它们整合到各种设备中。在本工作中,我们探索了使用药效团模型通过虚拟筛选来识别 DSSC 的无金属染料。基于实验测试的敏化剂建立药效团模型。针对从 ZINC15 库中获取的大量商用化合物数据集进行虚拟筛选,并确定了多个虚拟靶点。对这些靶点的一个子集进行 DFT 和时间相关的 DFT 计算,从而鉴定出两种化合物 TSC6 和 ASC5,它们具有适当的分子轨道能量、有利的定位和合理的吸收 UV-vis 光谱。这些结果表明,传统上用于药物发现和先导优化的药效团模型成功地预测了电子特性,这与敏化剂的理论要求一致。因此,此类模型可能会在材料科学中作为建模工具找到其他用途。

Editorial Summary

Power of Informatics: Performance Optimization of dye-sensitized solar cells

Dye sensitized solar cells (DSSC) are cost-effective, sustainable and versatile power supply units that can be integrated into various devices. However, the prediction of microstructure and properties is still a difficult problem for the rapid development of materials. The team of Professor Hanoch senderowitz from the Department of chemistry of Bar-Ilan University in Israel developed a new method to identify potential candidates for metal free dyes for DSSC using 3D pharmacophore models. Pharmacophore models were constructed from datasets of experimentally tested dyes and then used to screen the inventory portion of the zinc15 database containing more than 13.8 ? m compounds to retrieve those structures that match the relevant pharmacophore characteristics. The pharmacophore model was established based on the sensitizers tested in the experiment. Virtual screening was performed on a large number of commercial compound datasets obtained from the zinc15 library, and multiple virtual targets were identified. DFT and time-dependent DFT calculations were performed on a subset of these targets, and two compounds tsc6 and asc5 were identified, which have appropriate molecular orbital energy, favorable localization and reasonable absorption UV Vis spectra. These results indicate that the pharmacophore model has the ability to identify dyes with good (predicted) DSSC properties, thus building an important bridge between the spatial arrangement and electronic properties of simple chemical moieties. Crossing this bridge extends the use of ligand based pharmacophore models beyond its chemical informatics / drug design, into the field of materials science with many potentially exciting applications.

编辑概述

信息学的威力:染料敏化太阳能电池性能优化 

染料敏化太阳能电池 (DSSC) 是具有成本效益、可持续且用途广泛的电力供应单元,可以将它们整合到各种设备中。但是其微结构和性能预测仍是困扰材料快速开发的难题。来自以色列巴伊兰大学化学系的Hanoch Senderowitz教授团队开发了一种新方法,使用 3D 药效团模型来识别用于 DSSC 的无金属染料的潜在候选者。药效团模型是根据实验测试染料的数据集构建的,然后用于筛选包含超过 13.8?M 化合物的 ZINC15 数据库的库存部分,以检索与相关药效团特征匹配的那些结构。基于实验测试的敏化剂建立药效团模型。针对从 ZINC15 库中获取的大量商用化合物数据集进行虚拟筛选,并确定了多个虚拟靶点。对这些靶点的一个子集进行 DFT 和时间相关的 DFT 计算,从而鉴定出两种化合物 TSC6 和 ASC5,它们具有适当的分子轨道能量、有利的定位和合理的吸收 UV-vis 光谱。这些结果表明,药效团模型识别具有良好(预测)DSSC 特性的染料的能力,从而在简单化学部分的空间排列和电子特性之间构建了一座重要的桥梁。穿越这座桥将基于配体的药效团模型的使用扩展到其化学信息学/药物设计之外,进入具有许多潜在令人兴奋应用的材料科学领域。

On the role of the microstructure in the deformation of porous solids         
Sansit Patnaik, Mehdi Jokar, Wei Ding & Fabio Semperlotti     
npj Computational Materials 8: 152 (2022)
10.1038/s41524-022-00840-5
Published online: 18 July 2022
Abstract| Full Text | PDF OPEN

Abstract: This study explores the role that the microstructure plays in determining the macroscopic static response of porous elastic continua and exposes the occurrence of position-dependent nonlocal effects that are strictly correlated to the configuration of the microstructure. Then, a nonlocal continuum theory based on variable-order fractional calculus is developed in order to accurately capture the complex spatially distributed nonlocal response. The remarkable potential of the fractional approach is illustrated by simulating the nonlinear thermoelastic response of porous beams. The performance, evaluated both in terms of accuracy and computational efficiency, is directly contrasted with high-fidelity finite element models that fully resolve the pores’ geometry. Results indicate that the reduced-order representation of the porous microstructure, captured by the synthetic variable-order parameter, offers a robust and accurate representation of the multiscale material architecture that largely outperforms classical approaches based on the concept of average porosity.

摘要: 本研究探讨了微结构在确定多孔弹性连续体的宏观静态响应中所起的作用,并揭示了与微观结构的配置密切相关的位置相关非局部效应的发生。然后,发展了一种基于变阶分数阶微积分的非局部连续统理论,以准确捕捉复杂的空间分布非局部响应。通过模拟多孔梁的非线性热弹性响应来说明分数方法的显着潜力。从精度和计算效率两方面评估的性能与完全解析孔隙几何形状的高保真有限元模型直接对比。结果表明,由合成可变阶参数捕获的多孔微观结构的降阶表示提供了多尺度材料结构的稳健和准确的表示,该结构在很大程度上优于基于平均孔隙率概念的经典方法。

Editorial Summary

Light as a feather, strong as a rock: Design of porous materials

Porous materials can achieve low weight and high stiffness (high specific stiffness) at the same time. Naturally occurring porous materials include wood, marine shells and rocks. The pursuit of materials with high specific stiffness has long been the main pursuit of structural engineering, thus providing a revolutionary alternative to traditional materials such as alloys and composites. However, the research of porous materials is limited by technology and theory. At the technical level, the manufacture of porous materials is extremely challenging. At the theoretical level, it is still unclear how the size effect is generated from the underlying microstructure and affects the internal multi-scale response of materials. The team of Professor Fabio sempelotti from the school of mechanical engineering of Purdue University in the United States describes the internal nonlocal properties of porous solids by directly linking the size effect with the specific characteristics of porous microstructure. This method provides a solid physical foundation for the development of nonlocal continuum models with high accuracy and high computational efficiency. This study provides two key contributions to the physical understanding and modeling of porous media. First, it shows that porous solids exhibit location dependent nonlocal effects that cannot be ignored if accurate predictions are sought. Secondly, the nonlocal continuum theory which can capture these complex nonlocal effects is developed and tested numerically. The results show that this method provides a strict method to develop a physically consistent reduced order model of multi-scale systems, and its accuracy is comparable to that of a fully analytical 3D model. Although the results are proposed in the context of porous materials, the research framework can be extended to various applications with multi-scale characteristics, including but not limited to composite materials, building materials, seismology, biotechnology, etc..

编辑概述

轻如鸿毛、强如磐石:多孔材料的设计 

多孔材料能够同时实现低重量和高刚度(高比刚度),天然存在的多孔材料包括木材、海洋贝壳和岩石等,追求具有极高比刚度的材料长期以来一直是结构工程的主要追求,从而为合金和复合材料等传统材料提供了变革性的替代方案。但目前多孔材料的研究受限于技术和理论方面。在技术层面上,多孔材料的制造极具挑战性。在理论层面上,对尺寸效应如何从底层微观结构中产生并影响材料的内在多尺度响应的机理仍然不清楚。来自美国普渡大学机械工程学院的Fabio Semperlotti教授团队,通过将尺寸效应与多孔微观结构的特定特征直接联系起来,来描述多孔固体的内在非局部性质。这种方法为开发高精度和计算效率高的非局部连续统模型提供了坚实的物理基础,这项研究为多孔介质的物理理解和建模提供了两个关键贡献。首先,它表明多孔固体表现出与位置相关的非局部效应,如果寻求准确的预测,就不能忽视这些效应。其次,开发了能够捕捉这些复杂的非局部效应的非局部连续统理论并进行了数值测试。作者的研究提供了一种严格的方法来开发物理一致的多尺度系统降阶模型,其精度可与完全解析的 3D 模型相媲美。虽然结果是在多孔材料的背景下提出的,但本研究框架可以扩展到具有多尺度特征的各种应用,包括但不限于复合材料、建筑材料、地震学、生物技术等。

High-throughput computation and structure prototype analysis for two-dimensional ferromagnetic materials              
Zhen-Xiong Shen, Chuanxun Su & Lixin He   
npj Computational Materials 8: 132 (2022)
doi.org/10.1038/s41524-022-00813-8
Published online: 23 June 2022

AbstractWe perform high-throughput first-principles computations to search the high Curie temperature (TC) two-dimensional ferromagnetic (2DFM) materials. We identify 79 2DFM materials and calculate their TC, in which Co2F2 has the highest TC = 541 K, well above the room temperature. The 79 2DFM materials are classified into different structural prototypes according to their structural similarity. We perform sure independence screening and sparsifying operator (SISSO) analysis to explore the relation between TC and the material structures. The results suggest that the 2DFM materials with shorter distance between the magnetic atoms, larger local magnetic moments and more neighboring magnetic atoms are more likely to have higher TC.

摘要: 我们开展了基于第一性原理方法的高通量计算,搜索具有高居里温度的二维铁磁材料。我们筛选出了79个二维铁磁材料,其中Co2F2具有最高的居里温度,为541开尔文,远高于室温。为了研究居里温度与材料结构的关系,我们根据其结构相似性,将这79个二维铁磁材料分为不同的结构原型。我们使用压缩感知方法分析了居里温度和材料结构之间的关系,发现当材料中磁性原子间的距离更短、局域磁矩更大和具有更多的近邻磁性原子时,更可能具有高的居里温度。

Editorial Summary

2D ferromagnetic material working under high temperature: Based on?

Two dimensional (2D) systems were once considered as lacking long-range ferromagnetic order at finite temperatures. Recently, several two-dimensional ferromagnetic (2DFM) materials have been found in experiments, which has attracted extensive attention. 2DFM materials may have a wide range of applications, but at present, only few of them have been synthesized, and their Curie temperatures are very low. It is challenging to find 2DFM materials with high Curie temperature. This study identified 79 2DFM materials through high-throughput first-principles calculations, of which Co2F2 has a Curie temperature of 541 Kelvin, much higher than room temperature. The relationship between Curie temperature and material structure is also analyzed. Recently, the team led by Prof. He, Lixin from the University of science and technology of China calculated the phase diagrams and Curie temperatures of 79 2DFM materials, via the first-principles linear response theory and Monte Carlo simulations. In order to study the relationship between Curie temperature and material structure, the authors carried out cluster analysis on these two-dimensional materials, and obtained 11 structural prototypes with similar structures; The empirical estimation formulas of Curie temperature and structural parameters of two-dimensional magnetic materials are obtained by the Sure Independence Screening and Sparsifying Operator (SISSO) method. It suggests that smaller magnetic atom spacing, larger local magnetic moment and more adjacent magnetic atoms (e.g., structures with multiple magnetic layers) will make the 2DFM materials have higher Curie temperature.

编辑概述

具有什么结构特征的二维铁磁材料在更高温度下还保持铁磁性?

二维系统一度被认为在有限温度下不存在长程铁磁序。近期实验研究陆续发现了几种在有限温度下仍具有铁磁性的二维材料,引起了广泛关注。二维铁磁材料有广泛的应用前景,但是目前合成的二维铁磁材料还不多,且居里温度较低。寻找到高居里温度二维铁磁材料具有一定挑战性。最近来自中国科学技术大学的何力新教授团队,搜集了文献和数据库中大量的二维材料,并通过高通量计算寻找二维铁磁材料。他们采用基于第一性原理的线性响应理论计算了磁交换作用,并通过蒙特卡洛模拟计算材料的磁性相图和居里温度,最终确认了79个二维铁磁材料,其中Co2F2具有541开尔文的居里温度,远高于室温。为了研究居里温度与材料结构的关系,作者对这些二维材料进行了聚类分析,得到了结构相似的11个结构原型;借助压缩感知分析方法得到了二维磁性材料居里温度与结构参数的经验估值公式。该研究认为较小的磁性原子间距、较大的局域磁矩和更多的近邻磁性原子(如具有多层磁性原子的结构)会使二维铁磁材料拥有更高的居里温度。

Dynamical phase-field model of coupled electronic and structural processes              
Tiannan Yang & Long-Qing Chen   
npj Computational Materials 8: 130 (2022)
doi.org/10.1038/s41524-022-00820-9
Published online: 22 June 2022
Abstract| Full Text | PDF OPEN

AbstractMany functional and quantum materials derive their functionality from the responses of both their electronic and lattice subsystems to thermal, electric, and mechanical stimuli or light. Here we propose a dynamical phase-field model for predicting and modeling the dynamics of simultaneous electronic and structural processes and the accompanying mesoscale pattern evolution under static or ultrafast external stimuli. As an illustrative example of application, we study the transient dynamic response of ferroelectric domain walls excited by an ultrafast above-bandgap light pulse. We discover a two-stage relaxational electronic carrier evolution and a structural evolution containing multiple oscillational and relaxational components across picosecond to nanosecond timescales. The phase-field model offers a general theoretical framework which can be applied to a wide range of functional and quantum materials with interactive electronic and lattice orders and phase transitions to understand, predict, and manipulate their ultrafast dynamics and rich mesoscale evolution dynamics of domains, domain walls, and charges.

摘要: 许多功能材料与量子材料的功能来源于材料的电子与晶格两个子系统对于热、电、机械、光刺激等的共同响应。本文提出一种用于预测与模拟电子、结构的同步动态过程以及相应的介观尺度图案演化的动力学相场模型。作为应用范例,本文研究了铁电畴壁在高于带隙光脉冲激发下的暂态动力学响应。研究发现,系统的动态过程包含了两阶段弛豫型电子、空穴演化过程,以及由多个震荡型与弛豫型部分组成的结构演化过程,跨越了皮秒至纳秒级别时间范围。此模型可广泛应用于具有电子序、结构序与电子相变、结构相变相互作用的多种类别的功能材料与量子材料,为理解、预测、控制材料的超快动态过程以及包含畴、畴壁、电荷等的介观尺度演化的丰富信息提供了普适的理论框架。

Editorial Summary

Coupled electronic and lattice processes: A theoretical model for the nanoscale

The functionalities of a vast majority of functional materials are directly determined from the responses of both of their lattice and electron subsystems to external thermal, mechanical, and electromagnetic stimuli. Dynamical interactions among charge, orbit, and lattice degrees of freedom in these materials can give rise to coupled electronic and structural patterns and dynamical processes. The ability to theoretically predict and understand the coupled electronic and structural dynamics of materials is essential for both fundamental science and practical applications. A team led by Prof. Long-Qing Chen from the Department of Materials Science and Engineering, The Pennsylvania State University, USA, developed a novel dynamical phase-field model for predicting simultaneous electronic and structural processes and the accompanying evolution dynamics of nanoscale patterns, and predicted the light-excited charge and structural dynamics of ferroelectric domains for the first time. The work discovered a two-stage electronic carrier relaxation around a domain wall with a prolonged carrier lifetime by several orders of magnitude and a transient strain response containing several oscillational and relaxational components across picosecond-to-nanosecond timescales, providing useful theoretical insights on the rich simultaneous evolution dynamics of domains, domain walls, and charges. The work offers a general theoretical framework which can be applied to a wide range of functional materials with interactive electronic and lattice orders for understanding, predicting, and manipulating their dynamics and functionalities.

编辑概述

电子与晶格的耦合演化:纳米尺度理论模型

材料中的晶格系统与电子系统会对热、力、电磁等各种外界激励产生静态或动态的响应,两个子系统的共同响应直接决定了大多数功能材料的性能。而电荷、轨道、晶格等的动态相互作用,可进一步引发材料中电子与结构层面的纳米尺度图案及动力学过程的相互耦合。如何理论预测与理解电子与晶格于纳米尺度下的耦合动态过程,是研究材料动力学特性的关键。来自美国宾夕法尼亚州立大学材料科学与工程系的Long-Qing Chen教授团队提出了一种新型的动力学相场理论模型,该方法可模拟电子与晶格共同参与的纳米尺度微结构演化动力学,并首次理论预测了铁电畴的电荷与晶格系统在光学激发下的超快动态过程。研究显示,畴壁附近的电子、空穴浓度呈现两阶段弛豫型响应,载流子寿命延长了数个数量级,而应变呈现由多个震荡型与弛豫型部分组成的复杂响应,响应过程跨越皮秒至纳秒级别时间范围,揭示了畴结构、畴壁、电荷共同演化的丰富信息。该研究为多种功能材料中的电子与晶格序的动态耦合提供了普适的理论工具,以理解、预测、并控制材料的动力学行为与功能。

Anisotropic Dzyaloshinskii-Moriya interaction protected by D2d crystal symmetry in two-dimensional ternary compound              
Yonglong Ga, Qirui Cui, Yingmei Zhu, Dongxing Yu, Liming Wang, Jinghua Liang & Hongxin Yang   
npj Computational Materials 8: 128 (2022)
doi.org/10.1038/s41524-022-00809-4
Published online: 08 June 2022
Abstract| Full Text | PDF OPEN

AbstractMagnetic skyrmions, topologically protected chiral spin swirling quasiparticles, have attracted great attention in fundamental physics and applications. Recently, the discovery of two-dimensional (2D) van der Waals (vdW) magnets have aroused great interest due to their appealing physical properties. Moreover, both experimental and theoretical works have revealed that isotropic Dzyaloshinskii–Moriya interaction (DMI) can be achieved in 2D magnets or ferromagnet-based heterostructures. However, 2D magnets with anisotropic DMI haven’t been reported yet. Here, via using first-principles calculations, we unveil that anisotropic DMI protected by D2d crystal symmetry can exist in 2D ternary compounds MCuX2 (M: 3d transition metal (TM), X: group VIA). Interestingly, by using micromagnetic simulations, we demonstrate that ferromagnetic (FM) antiskyrmions, FM bimerons, antiferromagnetic (AFM) antiskyrmions, and AFM bimerons can be realized in the MCuX2 family. Our discovery opens up an avenue to creating antiskyrmions and bimerons with anisotropic DMI protected by D2d crystal symmetry in 2D magnets.

摘要: 磁斯格明子作为一种具有拓扑保护的手性自旋螺旋准粒子,在基础物理和应用中都引起了广泛的关注。近年来,二维(2D)范德华磁体(vdW)的发现由于其诱人的物理特性引起了人们的极大兴趣。此外,实验和理论工作都揭示了二维磁体或铁磁体基异质结构中可以实现各向同性Dzyaloshinskii-Moriya相互作用(DMI)。然而,具有各向异性DMI的二维磁体却罕有报道。本文通过第一性原理计算,揭示了二维三元化合物MCuX2 (M: 3d过渡金属(TM),X: VIA族)中存在受D2d晶体对称性保护的各向异性DMI。有趣的是,通过微磁模拟,我们证明了在MCuX2家族中可以实现铁磁(FM)反磁斯格明子、FM双半子、反铁磁(AFM)反磁斯格明子和AFM双半子。我们的发现为创造具有各向异性DMI的反磁斯格明子和双半子开辟了一条途径,这些DMI在二维磁体中受到D2d晶体对称性的保护。

Editorial Summary

Anti-topological spin textures are realized in two-dimensional ternary compounds protected by D2d crystal symmetry

Due to topological property, nano size and low drive current density of magnetic skyrmions make it an ideal information carrier for the next generation of spintronic storage or logic devices, such as orbital memory, reconfigurable logic gates, artificial neural devices for quantum computing with ultra-high density and low energy consumption of quantum bits. Recent work has revealed the realization of isotropic DMI Ne ?e ?l-type magnetic skyrmion, such as Cr(I,X)3, CrN and WTe2/Fe3GeTe2, in two-dimensional magnets with long range magnetic orderings. However, topological chiral magnetic structures with anisotropic DMI have not been reported in two-dimensional magnets. A team led by Prof. Hongxin Yang team From Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, via using first-principles calculations and atomistic spin model simulations confirm the anisotropic ferromagnetic (FM) skyrmions, FM bimerons, antiferromagnetic (AFM) skyrmions and AFM bimerons can be realized in layered van der Waals magnet MCuX2 (M: 3D Transition Metal (TM), X: VIA).

编辑概述

D2d晶体对称保护的二维三元化合物中实现反拓扑自旋结构

磁斯格明子的拓扑保护、纳米尺寸大小且驱动电流密度低的特性,使得其成为下一代自旋电子学存储或逻辑器件的理想信息载体,如轨道存储器、可重构逻辑门、人工神经元器件和用于量子计算的超高密度和低能耗的量子比特。新近发现二维(2D)长程磁序的磁体中可实现各项同性的Néel型斯格明子,如Mn(XY), Cr(X,Y) 以及WTe2/Fe3GeTe2等。然而,具有各向异性的拓扑手性磁结构还没有在二维磁体中得到证实。来自中国科学院宁波材料科学与工程技术研究所的杨洪新研究员团队,基于第一性原理计算和原子级自旋模拟,证实了各向异性的铁磁斯格明子、双半子和反铁磁反斯格明子、双半子可出现在层状单层范德瓦尔斯磁体MCuX2(M: 3d过渡金属(TM),X: 第六主族)中。此外,该研究还揭示了在连续的应力和温度变化下,单层VCuSe2的磁参数和手性磁结构的尺寸也将发生明显的改变,而且这种反磁斯格明子可以稳定在数百K的温度下。该研究对于未来范德瓦尔斯材料和自旋电子学器件的研究具有重要价值。

版权所有 © 中国科学院上海硅酸盐研究所  沪ICP备05005480号-1
地址:上海市长宁区定西路1295号 邮政编码:200050