Quasi-One-Dimensional Correlated Electronic Materials

9712765坎贝尔准一维关联电子材料为量子多体物理的发展提供了独特的机会。理论问题是容易处理的，比更高维度的问题更好。可以发展数值和理论技术，并将其与实验进行比较，并经常与现有的精确解进行比较。这项授予资深理论家的拨款支持两类相关的物理上相关的1D模型的工作，即Spin-Peierls和Peierls-Hubbard模型。这两类都涉及电子-电子相互作用和电子-声子相互作用之间的强烈相互作用，包括量子声子。这项研究利用了许多最先进的技术，最近发展起来的量子蒙特卡罗的两个变体，随机级数展开法和约束路径蒙特卡罗法。此外，还将使用精确对角化技术，利用最大熵技术进行解析延拓，并利用边界条件平均进行热力学极限的外推。对自旋磁化率、动态结构因子、核磁共振弛豫速率等物理观测数据进行了计算，并与实验结果进行了比较。随着对导电聚合物的技术兴趣的出现，凝聚态物质理论界找到了一个绝佳的机会。在这里，我们有复杂的系统，在一个维度上具有微妙的电子和机械属性。从数学上讲，后者是寻找复杂解决方案的最简单配置。它也被证明是一块了不起的试金石，复杂的理论技术可以在这里测试它们的适用性和准确性。这笔拨款是为了研究一些新发现的具有新性质的材料，并寻找人们可以使用尖端技术从理论上计算它们的方法。***

9712765 Campbell Quasi-one-dimensional correlated electronic materials offer a unique opportunity for progress in quantum many-body physics. The theoretical problems are tractable, better than in higher dimensions. The numerical and theoretical techniques can be developed and compared with experiments and often against available exact solutions. This grant to a senior theorist supports work on two related classes of physically relevant 1D models, spin -Peierls and Peierls- Hubbard models. Both classes involve strong interplay between electron-electron interactions and electron- phonon interactions, including the quantum phonons. The research makes use of many of the state-of-the-art techniques, two of the recently developed variants of quantum Monte Carlo, the Stochastic Series Expansion and Constrained Path Monte Carlo. In addition, use will be made of the exact diagonalization techniques, exploiting Maximum-Entropy techniques for analytic continuation and also boundary condition averaging for extrapolations to the thermodynamic limit. The calculations will be carried out for the physical observables such as, spin susceptibility, dynamic structure factors, NMR relaxation rates which will also be compared to the experiments. %%% With the advent of technological interest in conducting polymers, the community of condensed matter theorists has found a wonderful opportunity. Here we have complex systems with subtle electronic and mechanical properties in one dimension. The latter is mathematically the simplest configuration to look for complex solutions. It also proves to be a remarkable touchstone, one where the complex theoretical techniques can be tested for their applicability and accuracy. This grant is to consider some of the newly discovered materials with novel properties and to search for ways one can calculate them theoretically using cutting edge techniques. ***