Entangled-plaquette Variational Monte Carlo studies of strongly correlated electronic systems

强相关电子系统的纠缠斑块变分蒙特卡罗研究

• 批准号: 261547-2013
• 负责人: Boninsegni, Massimo
• 金额: $ 2.4万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633541
• 关键词: Entangled; plaquette; Variational; Monte; Carlo

The understanding of the physical mechanism underlying superconductivity at high temperature, in the copper-oxide compounds discovered 26 years ago, remains an outstanding and worthwhile goal of research in condensed matter theory. There is virtually universal agreement that the most important aspects of the phenomenology can be accounted for by strong electronic correlations existing in these materials. However, the accurate determination of the phase diagram of even the simplest lattice models of strongly correlated electrons, such as the t-J or Hubbard model, which are believed to capture the basic physics of high-temperature superconductors, has so far proven a task beyond the capability of even the most sophisticated existing analytical and numerical computational tools. Indeed, there continues to be no agreement as to whether the t-J and Hubbard model feature a superconducting ground state; all-important issues of direct experimental relevance, such as the appearance of stripes or the occurrence of phase separation at low hole doping, are still hotly debated. The purpose of this research effort is to utilize a very promising, recently introduced methodology, known as Entangled-Plaquette Variational Monte Carlo (EPVMC), to attempt to offer a definitive answer to the most important outstanding questions concerning the low temperature properties of the t-J or Hubbard model, chiefly the possible presence of a superconducting ground state. The EPVMC approach has proven effective in the investigation of "frustrated" magnetic systems, i.e., strongly correlated electronic models which had previously eluded a satisfactory theoretical analysis. It seems therefore to offer a possible avenue to the investigation of the above-mentioned strongly correlated electronic models. Because the application of EPVMC requires its extension and generalization to the case of electronic filling below one half (notably to the case of mobile vacancies) there is a potentially significant methodological development aspect to this proposed work as well.

对26年前发现的氧化铜化合物中高温超导性的物理机制的理解，仍然是凝聚态理论研究的一个突出和有价值的目标。事实上，人们普遍认为，现象学中最重要的方面可以通过这些材料中存在的强电子相关来解释。然而，即使是最简单的强关联电子的晶格模型的相图的准确测定，如t-J或哈伯德模型，这被认为是捕捉高温超导体的基本物理，迄今已被证明是一个任务，即使是最复杂的现有分析和数值计算工具的能力。事实上，对于t-J和哈伯德模型是否具有超导基态，仍然没有达成一致意见;与实验直接相关的所有重要问题，例如条纹的出现或低空穴掺杂时相分离的发生，仍然存在激烈的争论。这项研究工作的目的是利用一个非常有前途的，最近推出的方法，被称为纠缠-Plaquette变分蒙特卡罗（EPVMC），试图提供一个明确的答案，最重要的悬而未决的问题有关的t-J或哈伯德模型的低温性能，主要是超导基态的可能存在。事实证明，EPVMC方法在研究“受抑”磁系统（即，强相关的电子模型，以前逃避了令人满意的理论分析。这为研究上述强关联电子模型提供了一条可能的途径。由于EPVMC的应用需要将其扩展和推广到电子填补一半以下职位的情况（特别是移动的职位空缺的情况），因此这项拟议的工作也可能具有重要的方法学发展方面。