ITR: Study of Complex Nanoclustered States using Novel Efficient Algorithms

该奖项是应国际交易日志征集活动NSF-02-168提交的一个“小”类别提案而颁发的。它支持复杂纳米结构的计算和理论研究。一些化合物倾向于在纳米尺度上自发形成复杂的空间不均匀电子态。例子包括高温超导体、巨型磁阻锰氧化物和稀磁半导体。PI将使用自旋-费米子模型提供的简化框架来探索各种化合物中纳米团簇生成现象的起源。这些模型包含载流子和局域自旋自由度，也可能包含经典声子。研究涉及到一项仔细的计算工作，以捕捉该现象的渗流特征，并阐明复杂的非均匀电子基态的性质。使用目前可用的算法的研究人员已经能够揭示这些模型中令人惊讶的丰富结构，但由于严重的集群大小和CPU限制，进一步的进展是困难的。PI将进一步开发自旋-费米子哈密顿量的算法，以便能够访问足够大的系统大小，以便可以可靠地计算渗流纳米结构中的磁性和输运性质。这项研究将强调不同材料之间的相似性，并将有助于将使用类似自旋费米子模型的不同领域的研究联系起来。这项工作的一个方面涉及修改高能物理计算晶格规范理论社区的一个算法。在这项工作过程中开发的代码将提供给更广泛的材料理论社区。该奖项支持研究生在计算科学和物理方面的广泛教育经验，以及K-12学生在物理方面的教育经验。它还支持努力扩大代表性不足群体对科学的参与。这项研究使用计算来推进科学前沿的基本理论凝聚态物理。%该奖项是在回应ITR征集NSF-02-168时提交的一个小类别提案上颁发的。它支持复杂纳米结构的计算和理论研究。作为电子关联的结果，一些化合物倾向于自发地在纳米尺度上形成复杂的空间不均匀电子态。例子包括高温超导体、巨型磁阻锰氧化物和稀磁半导体。PI将使用自旋-费米子模型来探索空间不均匀电子态的起源。这些模型侧重于电荷载流子、局域自旋及其相互作用。研究涉及到一项仔细的计算工作，以阐明复杂的非均匀电子基态的性质。使用目前可用的算法的研究人员已经能够揭示这些模型中令人惊讶的丰富结构，但由于严重的集群大小和CPU限制，进一步的进展是困难的。PI将进一步开发用于自旋-费米子模型的算法，以实现对渗流纳米结构的磁性和输运性质的可靠计算。这项研究将强调不同材料之间的相似性，并将有助于将使用类似自旋费米子模型的不同领域的研究联系起来。这项工作的一个方面涉及修改高能物理计算晶格规范理论社区的一个算法。在这项工作过程中开发的代码将提供给更广泛的材料理论社区。该奖项支持研究生在计算科学和物理方面的广泛教育经验，以及K-12学生在物理方面的教育经验。它还支持努力扩大代表性不足群体对科学的参与。这项研究使用计算来推进科学前沿的基础理论凝聚态物理。

This award was made on a 'small' category proposal submitted in response to the ITR solicitation, NSF-02-168. It supports computational and theoretical research on complex nanostructures. Some compounds tend to spontaneously form complex spatially inhomogeneous electronic states on the nanoscale. Examples include high temperature superconductors, colossal magnetoresistive manganites, and dilute magnetic semiconductors. The PIs will explore the origins of the nanocluster generation phenomenon in a variety of compounds using a simplified framework provided by spin-fermion models. These models contain charge carrier and localized spin degrees of freedom; classical phonons may also be included. Research involves a careful computational effort to capture the percolating characteristics of the phenomenon and to elucidate the nature of complex inhomogeneous electronic ground states. Researchers using currently available algorithms have been able to unveil amazingly rich structures in these models, but further progress is difficult due to severe cluster-size and CPU limitations. The PIs will further develop algorithms for spin-fermion Hamiltonians to enable access to system sizes large enough so that magnetic and transport properties can be reliably calculated in percolative nanostructures. This research will emphasize the similarities among different materials and will help to relate investigations in different fields that use similar spin-fermion-like models. An aspect of this work involves modification of an algorithm from the computational lattice-gauge-theory community in high-energy physics. Codes developed in the course of this work will be made available to the broader materials theory community. This award supports broad educational experiences in computational science and physics for graduate students and educational experiences in physics for K-12 students. It also supports efforts to broaden participation of underrepresented groups in science. The research uses computation to advance fundamental theoretical condensed matter physics at the scientific frontiers.%%%This award was made on a 'small' category proposal submitted in response to the ITR solicitation, NSF-02-168. It supports computational and theoretical research on complex nanostructures. As a consequence of electronic correlations, some compounds tend to spontaneously form complex spatially inhomogeneous electronic states on the nanoscale. Examples include high temperature superconductors, colossal magnetoresistive manganites, and dilute magnetic semiconductors. The PIs will explore the origins of spatially inhomogeneous electronic states using spin-fermion models. These models focus on charge carriers, localized spins, and their interactions. Research involves a careful computational effort to elucidate the nature of complex inhomogeneous electronic ground states. Researchers using currently available algorithms have been able to unveil amazingly rich structures in these models, but further progress is difficult due to severe cluster-size and CPU limitations. The PIs will further develop algorithms for spin-fermion models to enable reliable calculations of magnetic and transport properties for percolative nanostructures. This research will emphasize the similarities among different materials and will help to relate investigations in different fields that use similar spin-fermion-like models. An aspect of this work involves modification of an algorithm from the computational lattice-gauge-theory community in high-energy physics. Codes developed in the course of this work will be made available to the broader materials theory community. This award supports broad educational experiences in computational science and physics for graduate students and educational experiences in physics for K-12 students. It also supports efforts to broaden participation of underrepresented groups in science. The research uses computation to advance fundamental theoretical condensed matter physics at the scientific frontiers.***