90年后,科学家揭示了苯的结构 诸平 Fig. 1 DVMS structures for benzene. a Voronoi site for the RHF/6-31G(d) wavefunction. The electron positions of an arbitrary spin are shown as small yellow spheres. b Cross sections through the wavefunction around the Voronoi site in a C–C bonding electrons are shown as blue lobes. C–H bonds are shown in grey. c. Voronoi site showing staggered spins. The electron positions of each spin are respectively shown as small yellow and green spheres. d. Cross sections around the Voronoi site in c. The two spins of the C–C bonding electrons are shown in blue and red. C–H bonds are shown in grey. Credit:Nature Communications(2020). DOI: 10.1038/s41467-020-15039-9 苯的结构是一名不知名的奥地利中学教师约瑟夫·劳施密特( Josef Loschmidt in full Johann Joseph Loschmidt , born May 15, 1821, Putschin, Bohemia, Austrian Empire —died July 8, 1895, Vienna , Austria ),早在 1861 年就已经得知苯环的结构了,这是在著名化学家凯库勒( Friedrich August Kekulé , 1829-1896 )梦里幻想苯环结构之前的事。因为 六元芳环在生物学中无处不在, 它是 DNA 和蛋白质以及木质生物质和石油 的组成部分 。芳族环和芳族结构在星际空间中观察到,在一般情况下,被认为是遍及星际介质。共轭六元环也是石墨烯的基本组成部分,石墨烯是具有惊人电子特性的材料。因此,对其结构的研究意义重大。 据澳大利亚研究委员会 ( Australian Research Council , ARC ) 激子科学卓越中心( ARC Centre of Excellence in Exciton Science )2020年 3 月 5 日提供的消息, 90 年后,科学家揭示了苯的结构。相关研究结果于 2020 年 3 月 5 日已经在《自然通讯》( Nature Communications )杂志网站发表—— Yu Liu , Phil Kilby , Terry J. Frankcombe , Timothy W. Schmidt . The electronic structure of benzene from a tiling of the correlated 126-dimensional wavefunction, Nature Communications , 2020, volume11, Articlenumber:1210. DOI: 10.1038/s41467-020-15039-9 图1是苯的DVMS结构。a. 是RHF/6-31G(d)波函数的Voronoi站点(Voronoi site)。任意自旋的电子位置显示为黄色小球。b. 在C-C键电子中,Voronoi站点周围波函数的横截面显示为蓝色瓣;C-H键显示为灰色。c. Voronoi站点显示交错旋转。每个自旋的电子位置分别显示为黄色和绿色小球。d. c中Voronoi站点周围波函数的横截面。C–C键合电子的两个自旋以蓝色和红色显示。C-H键显示为灰色。图片来源: Nature Communications (2020) . DOI: 10.1038/s41467-020-15039-9 .顺便介绍一下 Voronoi 图, Voronoi 图是一种重要的几何结构,它既是一种行之有效的空间剖分和聚类方法,又具有骨架的特性。它按照站点( sites )集合中元素的最近邻属性将空间划分成许多单元区域。在不同应用背景下,根据生成空间、测量距离以及站点等定义条件的不同,又产生了不同类型的 Voronoi 图。 ARC激子科学卓越中心、澳大利亚新南威尔士大学(University of New South Wales,UNSW)和澳大利亚联邦科学与工业研究组织(Commonwealth Scientific and Industrial Research Organization, CSIRO)之间的合作解决了化学的基本谜团之一,其结果可能会对太阳能电池,有机发光二极管和其他下一代技术的未来设计产生影响。 自20世纪30年代以来,化学界内部就苯的基本电子结构展开了激烈的争论。近年来,这种争论变得更加紧迫,因为包含六个碳原子和六个氢原子的苯(C 6 H 6 )是许多光电材料的基本组成部分,这正在彻底改变可再生能源和电信技术。扁平的六角环也是DNA、蛋白质、木材和石油的组成部分。围绕苯分子结构的争论之所以出现,是因为尽管它的原子成分很少,但电子以不仅包括四个维度(four dimensions,如我们日常的“大”世界),而且包括126个维度的状态存在。 到目前为止,分析复杂的系统被证明是不可能的,这意味着无法发现苯电子的精确行为。这就是一个问题,因为如果没有这些信息,该分子在技术应用中的稳定性将永远无法被完全理解。 但是,现在,由ARC卓越科学中心和新南威尔士大学悉尼分校(UNSW Sydney)的蒂莫西·施密特( Timothy Schmidt )领导的科学家,成功地揭开了谜底-结果令人惊讶。他们发表在《自然通讯》杂志上论文,解开了126个维度的谜团。 蒂莫西·施密特教授与来自UNSW和CSIRO的Data61( CSIRO’s Data61 )的同事们一起,对苯分子应用了一种基于动态Voronoi大都会采样(dynamic Voronoi Metropolis sampling, DVMS)的复杂算法,以便在所有126个维度上绘制其波函数。 解决复杂问题的关键是由合作者CSIRO的Data61菲尔·基尔比博士(Dr. Phil Kilby)开发的新数学算法。该算法允许科学家将维空间划分为等效的“平铺”(equivalent tiles),每个平铺对应于电子位置的排列。 科学家特别感兴趣的是理解电子的“自旋”。所有电子都有自旋 , 这是产生磁力以及其他基本力的特性,但它们如何相互作用是从发光二极管到量子计算的广泛技术之基础。 蒂莫西·施密特教授说:“我们发现的结果非常令人惊讶。”“既有具有上自旋双键的电子,也有具有下自旋单键的电子,反之亦然。”“这并非化学家对苯的想法。本质上,它通过使彼此排斥的电子相互排斥,从而降低了分子的能量,使其更稳定。” 来自Data61的合作者菲尔·基尔比博士补充说:“尽管是针对这种化学背景而进行的开发,但是我们为“与约束条件匹配”而开发的算法 , 其应用范围并非仅仅而已,它也可以应用于从工作人员名册到肾脏交换计划的广泛领域。”更多信息请注意浏览原文或者相关报道。如理论家们最终证明,“弯箭”能说明化学反应的真相( Theoreticians finally prove that 'curly arrows' tell the truth about chemical reactions )—— Yu Liu , Philip Kilby , Terry J. Frankcombe , Timothy W. Schmidt .Calculating curly arrows from ab initio wavefunctions. Nature Communications , 2018,Volume9, Articlenumber:1436. DOI: 10.1038/s41467-018-03860-2 Abstract The electronic structure of benzene is a battleground for competing viewpoints of electronic structure, with valence bond theory localising electrons within superimposed resonance structures, and molecular orbital theory describing delocalised electrons. But, the interpretation of electronic structure in terms of orbitals ignores that the wavefunction is anti-symmetric upon interchange of like-spins. Furthermore, molecular orbitals do not provide an intuitive description of electron correlation. Here we show that the 126-dimensional electronic wavefunction of benzene can be partitioned into tiles related by permutation of like-spins. Employing correlated wavefunctions, these tiles are projected onto the three dimensions of each electron to reveal the superposition of Kekulé structures. But, opposing spins favour the occupancy of alternate Kekulé structures. This result succinctly describes the principal effect of electron correlation in benzene and underlines that electrons will not be spatially paired when it is energetically advantageous to avoid one another.
引用自: https://www.maplesoft.com/products/toolboxes/quantumchemistry/ Quantum Chemistry Toolbox from RDMChem Predict, explore, and design novel molecules in a powerful, easy-to-use environment The Maple Quantum Chemistry Toolbox from RDMChem combines modern quantum chemistry software techniques with the mathematical power and usability of Maple to provide a comprehensive, easy-to-use environment for the parallel computation of the electronic energies and properties of molecules. With this toolbox, you can: Define molecules instantly from a database of more than 96 million molecules Run quantum computations with well-known electronic structure methods as well as recently developed advanced methods, enabling cutting-edge research Analyze molecular energies and properties through publication-quality, 2-D and 3-D plots and animations. The toolbox includes density functional theory and wave function methods as well as advanced reduced density matrix (RDM) techniques. The RDM techniques, which are unique to the toolbox, are well-suited for strongly correlated molecules where they can accurately describe quantum effects that are difficult to treat by conventional methods. The Quantum Chemistry Toolbox is designed and implemented by RDMChem LLC , which was founded to develop the next generation of computational chemistry software with applications to engineering, molecular biology, and physics. Key Features Instant definition of molecules from a database of over 96 million molecules Easy-to-use Maple commands for state-of-the-art parallel electronic structure methods Access to modern 2-RDM methods for advanced treatment of highly correlated molecules Molecular geometry optimization powered by Maple’s state-of-the-art optimization solvers Easy computation and analysis of quantum-mechanical and thermodynamic properties Interactive 3-D plots of molecules and molecular orbitals inside your Maple document Interactive 3-D animations of molecular vibrations Interactive Maplet interface for rapid exploration of a molecule and its properties Maple commands that can handle the most demanding computations Curricula and lessons for using the toolbox in Chemistry and Physics courses Automatic parallelization of computations Seamless integration with Maple, including: Over 5000 commands for scientific and mathematical computations, which can be used to analyze and extend results Powerful Maple programming language designed for mathematics, enabling the manipulation of results without low-level programming Technical document interface that supports computations, text, plots, images, and much more, all in a single, sharable document Advanced connectivity for exporting results to C, Fortran, Python, Excel, LaTeX, MATLABreg;, and more Application Areas The Maple Quantum Chemistry Toolbox from RDMChem can be used to study, understand, predict, and design molecules for applications in engineering, molecular biology, and physics. You can: Explore chemistry structure and reactivity Design and analyze novel molecules and materials Predict and verify synthetic pathways in chemistry and biology Engineer molecules for energy transfer, storage, and release Model catalysis in chemistry and biochemistry Design molecules for pharmaceutical RD Treat strongly correlated organometallic complexes Bring quantum mechanics and chemistry to life in the classroom and much more! Why Use the Maple Quantum Chemistry Toolbox? Researchers Accelerate your research Explore all of the quantum possibilities for your molecular application with the toolbox’s state-of-the-art electronic structure methods. Save time in your computations by combining electronic structure calculations with Maple’s powerful symbolic and numeric math engine and flexible visualization tools to tackle the most difficult chemical challenges. Educators Engage your students Whether you teach at the undergraduate, graduate, or high school level, the Quantum Chemistry Toolbox and its trove of built-in curricula and lessons provide an exciting and dynamic way to introduce students to the critical role of quantum mechanics in chemistry . From an understanding of chemical bonding and energy levels to rotational and vibrational spectroscopy, static concepts in the text come alive through real-time quantum chemistry computations and visualizations . Students Enhance your understanding of chemistry and physics Give yourself an edge! Using the Quantum Chemistry Toolbox, you can quickly deepen your understanding of molecular concepts in a way that is simply not possible from textbooks, even after hours of studying. The toolbox, together with its built-in curricula and lessons, is ideal for undergraduate and graduate students in chemistry and physics . Maplesoft China No.968 West Beijing Road, Shanghai Email: china@maplesoft.com Tel: 021-52037605 www.maplesoft.com
离域化误差是困扰密度泛函近似的主要误差之一,广泛存在于各种体系的计算中。消除离域化误差是数十年来颇具挑战的一个课题。 《国家科学评论》( National Science Review ,NSR) 最近发表了由美国杜克大学以及中国科技大学的合作研究团队( 李晨 博士、 郑晓 教授、 苏乃强 博士以及 杨伟涛 教授)撰写的研究论文: Localized Orbital Scaling Correction for Systematic Elimination of Delocalization Error in Density Functional Approximations ,他们研发了一种局部轨道标度修正(LOSC)泛函,成功实现系统性消除离域化误差。 离域化误差主要体现为Kohn-Sham (KS)轨道能以及体系总能量这两方面误差,且二者都呈现出随体系大小而消长的趋势。具体来说,理想情况下最高占据轨道能(HOMO)应当严格等于(负的)垂直电离能(- I ve );而 I exp 应当与实验值 I exp 相符。然而现有的泛函近似,例如LDA泛函,产生如图(a)所示的误差,且两种误差随体系增大此消彼长,呈现互补之势。类似的误差普遍存在于其他泛函中,诸如图示B3LYP泛函。 以上问题可以归结为分数体系的能量误差。正确的分数体系能量应随分数电子数n (0≤n≤1)线性变化(线性标度)。就此如果我们就分数体系氦原子能量对正确线性的偏离作图,会得到如图(b)所示的图像。很显然,分数体系能量被严重低估,这也即是离域化误差的定义。此外,图(b)中分数体系的误差与图(a)中整数体系的误差Δ I 一一对应。这意味着如果图(b)中单个氦原子的问题得到修正,且该修正保持体系大小一致性,那么离域化误差就将被一网打尽。 就此问题,研究者们创新性地引入一组特殊的局域轨道,称作小轨道(orbitallets),兼具空间与能量双重局域性。用这组小轨道作基矢,密度矩阵得以被局域化表示,从而自然地得到由分数组成的局域占据数矩阵λ。这些局域变量精准地捕捉到了局部分数电子分布信息,因此成为构建LOSC泛函的重要元素。此外,研究者们还设计了与λ矩阵相对应的局域曲率矩阵κ,每个矩阵元素分别是小轨道的泛函。最后LOSC修正公式借由λ与κ矩阵元素表示出来。 作者通过大量实例证明LOSC达到了设计者的初衷。例如附图中LOSC误差降到几乎可以忽略。此外,二聚体正离子分子解离曲线得到极大改进;中小分子、多聚体分子HOMO, LUMO能量误差被大大降低,且误差不依赖于体系大小;当母泛函给出错误的电子密度时,LOSC能够将密度改对。 以上种种实例证明了LOSC在系统性消除离域化误差方面取得成功。值得注意的是,与传统的泛函不同,LOSC没有采用密度、密度梯度、动能密度等等构建修正泛函,而是设计了全新的变量,即小轨道,其本身是密度矩阵的隐泛函。在这一点上LOSC改变了传统泛函的范式,大大拓宽了设计泛函的空间,凭此引领了新一代泛函发展的潮流。 文章信息: Localized Orbital Scaling Correction for Systematic Elimination of Delocalization Error in Density Functional Approximations Chen Li, Xiao Zheng, Neil Qiang Su, Weitao Yang Natl Sci Rev , 2017, doi: 10.1093/nsr/nwx111 全文链接 : https://doi.org/10.1093/nsr/nwx111
International Journal of Quantum Chemistry 特刊:理论化学在中国 过去的 50 年中,自从唐敖庆院士为中国的量子化学奠定基础以来,中国的科研团体对现代理论化学的研究做出了重要的贡献。本期特刊由 刘文剑教授 ( 北京大学化学与分子工程学院 )与 方维海教授 (北京师范大学化学学院)主编,从 3 期 International Journal of Quantum Chemistry 期刊中精选文章,期望能够以此勾勒今天的大陆与香港学者在 理论化学与计算化学领域 所做的研究,体现中国量子化学研究多样性、极具活力及前瞻性的特色。 点击链接 免费阅读本期特刊: http://onlinelibrary.wiley.com/doi/10.1002/qua.v115.11/issuetoc http://onlinelibrary.wiley.com/doi/10.1002/qua.v115.10/issuetoc 欢迎光临 Wiley 在 6 月 8-13 日在清华大学举办的国际量子化学大会上的展位,现场会发放精美礼品哦! 精选内容: Cover Image, Volume 115, Issue 9 (pages i–ii) Article first published online: 16 MAR 2015 | DOI: 10.1002/qua.24906 This perspective, Xingyong Wang, Tianying Yan and Jing Ma (DOI: 10.1002/qua.24829 ) give a brief overview of recent developments of polarizable force fields (FFs) – a kind of specific FF method that includes polarization effect into conventional molecular mechanics (MM). The commonly adopted polarizable models, i.e., the fluctuating charge (FQ) model, Drude model, and the inducible dipole (ID) model are expatiated. Taking advantage of the recent development of computational techniques and fragment-based low-scaling quantum mechanics (QM) methods, QM-based polarizable FFs appeared and particularly aroused great interest in biological systems. Current applications and limitations of several models are discussed. Opportunities and challenges for future development are also addressed. Cover Image, Volume 115, Issue 9 (pages iii–iv) Article first published online: 16 MAR 2015 | DOI: 10.1002/qua.24907 Lu Han, Yaling Ke, Xinxin Zhong and Yi Zhao (DOI: 10.1002/qua.24833 ) report on electron-hole pair formation in a one-dimension organic molecule chains excited by sunlight and the carriers transported along the chain . Meanwhile, the populations dependent on the time reflect the evolution processes for the wavepacket. Perspectives 1. Potential generation and path-integral Monte Carlo in study of microscopic superfluidity (pages 535–540) Tao Zeng, Hui Li and Pierre-Nicholas Roy Article first published online: 15 NOV 2014 | DOI: 10.1002/qua.24815 Microscopic superfluidity can be demonstrated in microscopic Andronikashvilli experiments. In theory, it can be modeled through simulations of quantum rotation of molecular rotors embedded in microscopic superfluids such as 4 He and para -H 2 . The methodologies used in generating accurate rotor-solvent potential energy surfaces, and the path-integral Monte Carlo method that is used in the actual simulations, are reviewed in this article, which aims to serve as a mini tutorial review for the subject of microscopic superfluidity. 2. Understanding the microsolvation of salts in molecular clusters (pages 541–544) Cheng-Wen Liu and Yi Qin Gao Article first published online: 3 DEC 2014 | DOI: 10.1002/qua.24827 The microsolvation of salts in water can be qualitatively understood using molecular cluster models. However, for large clusters the high-dimensional potential energy surface can be quite complex. The combination of enhanced molecular dynamics simulations and quantum chemical calculations can overcome this problem. The microsolvation of three alkali–halide ion pairs is used to illustrate this methodology, leading the discussion on future work and challenges in modeling salt–water and salt–water–organic systems. 3. Polarizable force fields based on physical models and quantum chemical calculations (pages 545–549) Xingyong Wang, Tianying Yan and Jing Ma Article first published online: 20 NOV 2014 | DOI: 10.1002/qua.24829 Nonpolarizable force fields cannot guarantee the accurate calculation of optical dielectric constants. The parameterization of polarizable FFs is not trivial, but electrostatics approaches, like the FQ model, Drude model, and the ID model, as well as fragment-based low-scaling QM methods show great potential in the hands of the community of developers. Reviews 1. Generalized time-dependent approaches to vibrationally resolved electronic and Raman spectra: Theory and applications (pages 550–563) Wanzhen Liang, Huili Ma, Hang Zang and Chuanxiang Ye Article first published online: 27 NOV 2014 | DOI: 10.1002/qua.24824 Vibronic spectroscopy involves simultaneous changes in the vibrational and electronic energy states of a molecule. Its calculation requires both the knowledge of quantum dynamics and advanced electronic structure theory. This review summarizes the general time-dependent approaches on a series of vibronic spectra with inclusion of Frank–Condon, Herzberg–Teller, and mode mixing effects. The numerical applications to one/two-photon absorption and emission, and Raman spectra are demonstrated. 2. Modeling the low frequency vibrational spectroscopy of ionic solutions (pages 564–569) Ruiting Zhang, Zhijun Pan and Wei Zhuang Article first published online: 28 NOV 2014 | DOI: 10.1002/qua.24826 Low frequency vibration spectroscopy plays a unique role in studying the interaction between ions and water molecules. This review discusses some recent efforts in modeling and analyzing the low frequency vibration spectra of ionic solutions. Issues in current theoretical simulation and concerns for further investigations are also addressed. 3. Economical basis sets and their uses in ab initio calculations (pages 570–577) Rui-Qin Zhang and Wen-Jie Fan Article first published online: 8 DEC 2014 | DOI: 10.1002/qua.24830 The roles of the particular functions composing a basis set, including the polarization and diffuse functions, as well as the nature and environment of each atom in a molecule need to be considered to choose the most appropriate basis in ab initio calculations. The number and level of basis functions required to describe an atom should increase from left to right in terms of its appearance in the periodic table and the relative increase in electronegativity. 4. Time-dependent wavepacket diffusion method and its applications in organic semiconductors (pages 578–588) Lu Han, Yaling Ke, Xinxin Zhong and Yi Zhao Article first published online: 2 DEC 2014 | DOI: 10.1002/qua.24833 In organic materials, the carrier-phonon interaction plays an important role for the carrier transport process. The time-dependent wavepacket diffusion (TDWPD) method has been developed to model carrier dynamics from coherent band-like to hopping-type regimes. The results demonstrate that TDWPD can accurately predict the carrier dynamics of systems from small compounds to nanoscale materials including thousands of molecules. TDWPD can be effectively combined with electronic structure calculations and tackle realistic models of organic semiconductors.
徐光宪精神——“国家需要”始终是第一位的 诸平 中国稀土之父徐光宪 徐光宪(1920年11月7日-2015年4月28日),浙江 上虞 人,著名物理化学家, 无机化学 家,教育家, 中国科学院院士 。1991年被选为亚洲化学联合会主席。曾任 北京大学 化学系教授、博士生导师、中国科学家协会会长。历任北京大学 原子能 系(后改为技术物理系)副主任、 稀土 化学研究中心主任,国家自然科学基金委员会化学科学部主任,第二十二届中国化学学会理事长,中国稀土学会名誉理事长,全国人大代表,全国政协委员等职。著作有《 物质结构 》、《量子化学》、《稀土的溶剂萃取》、《稀土》(上下册)、《萃取化学原理》等。 徐光宪教授是 2008年度国家最高科学技 术奖得主、被誉为中国稀土之父,于2015年4 月28日上午去世,享年95岁。 徐光宪教授 出 1920年 生于浙江 上虞 , 1944年毕业于交通大学化学系, 1946年任交通大学化学系助教, 1947年赴美留学,1951年获美国哥伦比亚大学物理化学博士学位,不久回国,到北京大学任教、从事研究。1980年,当选为中国科学院学部委员(院士)。主要从事量子化学、配位化学、稀土化学及萃取化学等方面的科研和教学工作,并注重自然辩证法和科学方法论的研究。徐光宪教授在20世纪50年代 提出的核外电子排布经验规则(n+0.7l)至今仍然在大学《无机化学》、《结构化学》中被应用,仅有少数例外;徐光宪教授编写的《物质结构》作为大学教材被应用有半个多世纪了,是一本经典的结构化学教科书 。当然他在稀土元素分离方面的研究,可以认为是“中国传奇”。 他和他的研究团队将自己的相关理论运用于实际生产,依靠自己的努力攻关,使中国在稀土分离技术上走在世界的最前列,短短十几年从一个稀土“匮乏”大国一跃成为世界上最大的稀土出口国,并占据了国际市场80%的份额,造就了一个关于稀土的“中国传奇”。 1951年 在美国哥伦比亚大学 获 得 物理化学博士学位 后不久,徐光宪携夫人高小霞怀着报效祖国的理想,几经艰难终于回到了自己的祖国,回国后再北京大学任教。1972年,北京大学化学系接受了一项紧急任务——分离镨钕,纯度要求很高。徐光宪成了这一研究的主要负责者。从量子化学的教学与研究转到配位化学,已经是一个很大的跨越了,但是徐教授并不这样认为,在他的心中,祖国需要高于一切,祖国需要就是最高任务,为了能源问题又转到核燃料化学,最后再转到稀土化学,这已是徐光宪第四次改变研究方向了。对他来说,“国家需要”始终是第一位的理由。 徐光宪以其特有的学术敏感,从改进稀土萃取分离工艺入手,使镨钕分离系数打破了当时的世界纪录。他建立自主创新的串级萃取理论,推导出100多个公式,并成功设计出了整套工艺流程,实现了稀土的回流串级萃取。他率先办起“全国串级萃取讲习班”,使新的理论和方法广泛用于实际生产,大大提高了中国稀土工业的竞争力。 有人曾问徐光宪,一生中最感到满意的事是什么?徐光宪却立即答道:“是培养了一批好学生。”几十年来,徐光宪不仅培养了近百名博士生和硕士生,还为我国稀土产业界培养了大批工程技术人员。现在在北大稀土国家重点实验室工作的他的学生中,就有中国科学院院士3人、长江学者特聘教授3人。 众所周知, 中国是稀土资源大国。由于国家的重视,经过40年的努力,我国已形成了技术力量很强的稀土科研、生产、教学专业队伍。据1989年统计,全国约有5300人从事稀土研究,其中2800人具有高级技术职称,分布在81个研究单位和42所高等学校。为了开发稀土资源,我国科技人员从本世纪50年代起,大力开展提取工艺及化学基础的研究,如对溶液络合物、离子交换、溶剂萃取,特别是对萃取剂的合成、性质、结构以及串级萃取理论等进行了广泛深入的研究。这些研究推动了稀土分离工艺的发展,使我国稀土分离工艺处于国际先进水平。中国以大量质优价廉的稀土产品进入世界市场,一举改变了稀土的产销格局,并使1993年单一稀土纯氧化物、金属和NdFeB等产品的价格下降到只有1984年的1/5到1/3。这是继20世纪40年代离子交换法代替分级结晶法的第一次飞跃和60年代用溶剂萃取法代替离子交换法的第二次飞跃后的又一次价格大幅度下降,从而大大有利于稀土的推广应用。1986年,我国的稀土年产量已超过美国而跃居世界第一位,年消费量为世界第二位。徐光宪教授主编的《稀土》(上下册)已经连续出版了第一版和第二版;其他论著如 Rare earth (2) X Guangxian - 1995 - footprintfiend.com New frontiers in rare earth science and applications X Guangxian - 2012 - books.google.com THE STUDY OF MECHANISM OF CHELATE AND SYNERGISTIC EXTRACTIONS BY THE METHOD OF TWO-PHASE TITRATIONS L Lemin, X Guangxian - Chemical Research In Chinese Universities, 1981 - en.cnki.com.cn Crystal structure of two neodymium complexes with amino acids:{ (ClO 4) 6· 3H 2 O n} and (ClO 4) 6· H 2 O …, W Xiaoqing, J Tianzhu, Z Shiwei, X Guangxian - Journal of alloys and …, 1994 - Elsevier 在怀念徐光宪教授的同时,更应该继承徐光宪精神—— “国家需要”始终是第一位的,少一点虚的SCI论文,多一点与生产实践相结合的东西,帮助解决实际问题,可能就是实现中国梦的最好归宿。 相关介绍: 深切缅怀徐光宪先生:莫道桑榆晚,霞光尚满天 ; 徐光宪与《稀土的溶剂萃取》 ; 光宪路永在, 吾辈不相忘 ; 旧文章缅怀徐老
2014年3月31日~4月1日,“ 2nd International Symposium of Theoretical Chemistry Center, Tsinghua University (TCC-THU)” 国际研讨会在清华大学召开。大会围绕“ Quantum Chemistry forExtended Systems ”这一主题邀请了该领域国内外诸多专家进行了学术报告及研讨。同时,大会期间正值国际著名量子化学专家 Jean-Marie André 教授70寿诞,因此会议主席、 Science China Chemistry 编委、清华大学 帅志刚 教授特为刊物组织了“ Quantum Chemistry for Extended Systems — In honor of Prof. J.M. André for his 70th birthday ”专辑。专辑于2014年第10期(2014, 57(10), 1315—1426)正式出版。 专辑邀请了参会的国内外专家针对本领域的前沿及进展撰写了13篇优秀稿件,其中国外稿件8篇。希望本次专辑的出版能使更多的专家学者了解该领域的相关进展。 欢迎访问该专辑: