Strong Correlation meets Materials Modelling: DMFT and GW in CASTEP

强相关性与材料建模的结合：CASTEP 中的 DMFT 和 GW

• 批准号: EP/M010880/1
• 负责人: Keith Refson
• 金额: $ 36.16万
• 依托单位: Royal Holloway University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FM010880%2F1
• 关键词: Strong; Correlation; meets; Materials; Modelling

The function of much modern technology is based on exploiting special physical properties of materials. This might be control of electrical current in the case of semiconductors, magnetism for data storage, the Peltier effect for solid-state refrigerators, or superconductivity for ultra high power magnets used in MRI scanners. Underpinning future refinements of such "functional materials" and development of new materials and devices lies the idea of "materials design". Computer simulation methods with the power to predict the active properties based only on the quantum-mechanical behaviour of the electrons in a particular crystal structure are a vital part of any attempt to engineer "designer materials" for future devices.The proposers of this grant are among those responsible for writing the CASTEP density-functional theory (DFT) modelling code, which is among the top few modelling codes used on the previous generation HECToR national high-performance computing service. CASTEP is licensed to nearly 100 UK research groups, was used to generate 118 research publications in 2013 and a worldwide total exceeding 4000.Density-functional theory is the simulation method of choice for a large part of modern materials science, condensed matter physics and solid-state chemistry. It can treat a huge range of materials, including bulk metals, oxides, semiconductors, layered materials such as graphene, surfaces and much more. It is widely used to predict structural and energetic properties such as phase transitions, electronic transport properties, spectroscopic properties including NMR chemical shifts, inelastic neutron and X-Ray, Raman and infrared, XANES and other near-edge electronic spectra.However, its success is not universal. The essential approximations to exchange and correlation (ie the LDA, GGAs and hybrids) have poor predictive power for many materials containing open d- and f-shells, frequently described as "strongly-correlated". For example many transition-metal oxides are erroneously predicted by LDA and GGA to be metallic, Jahn-Teller structural distortions are absent and phase transitions involving electron delocalisation are not reproduced.Methods for treating strongly-correlated systems which remedy the deficiencies of semi-local DFT include dynamical mean-field theory (DMFT) and the so-called GW approximation. However these are currently not readily accessible to the materials modelling community, partly because of computational expense and partly because of the lack of robust, easily deployable modelling codes.Herein we propose to implement both LDA+DMFT and GW within CASTEP, the UK's premier electronic structure-based materials modelling code. Our strategic target is to substantially broaden the strong-correlation modelling community in the UK, which is currently small compared to either France or Germany. The planned deliverables will offer both an extension to CASTEP with end-user capability, but also a software platform for further development of the methodology. A key feature of our DMFT implementation will be the availability of forces, and capability of structure optimization. This will enable a realistic treatment of complex materials with low site symmetry. We hope this will stimulate an growth in the adoption of these methods in the UK from the developer groups to a wider modelling community much as happened with DFT.The power of simulation works best when used hand in hand with experimental studies. The UK has invested heavily in instruments targeted at "strongly-correlated" materials in the RIXS and ARPES beamlines at Diamond Light Source and the MERLIN instruments at ISIS target station 2 neutron facility. A key feature of this proposal is to work with scientists at both facilities to deliver the capability of modelling some of the actual materials selected for experimental study by the scientific user community. We believe this will maximise the impact of the work.

许多现代技术的功能是基于利用材料的特殊物理特性。在半导体的情况下，这可能是对电流的控制，数据存储的磁性，固态冰箱的毛皮效应或用于MRI扫描仪中超高功率磁铁的超导性。为这种“功能材料”和新材料和设备的开发的未来改进的基础是“材料设计”的想法。具有能力的计算机模拟方法仅基于特定晶体结构中电子的量子力学行为来预测活动性能，这是任何为未来设备设计“设计师材料”的尝试的重要组成部分。该赠款的建议者是负责编写Castep密度官能官方官方式（DFT）建模的人之一，而这些代码是对以前的建模代码，该代码是在较高的国家模型中使用的。 Castep已获得近100个英国研究小组的许可，用于2013年生成118个研究出版物，全球总数超过4000.密度功能理论是现代材料科学，凝结物理学和固态化学的大部分仿真方法的仿真方法。它可以处理大量材料，包括散装金属，氧化物，半导体，分层材料，例如石墨烯，表面等等。它被广泛用于预测结构和能量性能，例如相变，电子传输特性，光谱特性，包括NMR化学移位，非弹性中子和X射线，拉曼和红外，XANES和其他近乎边缘电子光谱。交换和相关性的基本近似值（即LDA，GGA和杂种）对于许多含有开放式D和F壳的材料的预测能力较差，这些材料经常被描述为“强相关”。例如，通过LDA和GGA错误地预测了许多过渡金属氧化物是金属的，Jahn-Teller的结构扭曲不存在，并且没有复制涉及电子离系数的相变的相变。处理强大的系统，这些系统可以补救强烈的系统，这些系统弥补了半元素的偶然性均匀的均匀型号（dmimical nimical nimical nimical dyimical and-fft）。但是，目前这些材料建模社区目前不容易访问，部分原因是由于计算费用，部分原因是由于缺乏强大，易于部署的建模代码。我们的战略目标是实质上扩大英国的强相关建模社区，该建模社区目前与法国或德国相比很小。计划中的可交付成果将既可以通过最终用户功能为Castep提供扩展，又可以为进一步开发方法的软件平台提供扩展。我们DMFT实施的关键特征将是力的可用性以及结构优化的能力。这将使用低位点对称性的复杂材料进行现实处理。我们希望这将刺激英国采用这些方法的增长，从开发人员群体到DFT的更广泛的建模社区。仿真的功能在与实验研究中并驾齐驱时最有效。英国在钻石光源的Rix和Arpes梁上的材料和ISIS Target Station 2 Neutron设施的Merlin Instruments的Rix和Arpes束线上的材料中进行了大量投资。该提案的一个关键特征是与这两个设施的科学家合作，以提供对科学用户社区选择的一些实际材料进行建模的能力。我们相信这将最大程度地发挥作品的影响。

项目成果

Many-body renormalization of forces in f -electron materials

• DOI: 10.1103/physrevb.98.075129
• 发表时间: 2018-04
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: E. Plekhanov;P. Hasnip;V. Sacksteder;Matt Probert;S. Clark;K. Refson;C. Weber