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Full-Text Articles in Physical Sciences and Mathematics

Synthesis And Computational Studies Of A New Class Of Lanthanide Niobate Cluster : [Ln4(H2O)8(So4)5(Nbo3)2]+3h2O; Ln= Dy, Tb, Brady D. Garabato Aug 2013

Synthesis And Computational Studies Of A New Class Of Lanthanide Niobate Cluster : [Ln4(H2O)8(So4)5(Nbo3)2]+3h2O; Ln= Dy, Tb, Brady D. Garabato

Masters Theses & Specialist Projects

Polyoxoniobates (PONbs) are a small family of highly electron-rich clusters. The development of new solids composed of these clusters have applications in green energy and electronics. However, the high charge environment of PONbs typically requires alkaline synthetic conditions that are unsuitable for introducing other metals and organic molecules, making synthesis of new systems difficult. To date, very few transition metals and organic ligands have been incorporated into these PONb solids, and lanthanide metal inclusion, which generally improves photoconductivity due to longlived f-orbital excitations, has not yet been fully realized. Here, the synthesis of a new class of lanthanide niobate cluster …


A Short Introduction To Numerical Linked-Cluster Expansions, Baoming Tang, Ehsan Khatami, Marcos Rigol Mar 2013

A Short Introduction To Numerical Linked-Cluster Expansions, Baoming Tang, Ehsan Khatami, Marcos Rigol

Faculty Publications

We provide a pedagogical introduction to numerical linked-cluster expansions (NLCEs). We sketch the algorithm for generic Hamiltonians that only connect nearest-neighbor sites in a finite cluster with open boundary conditions. We then compare results for a specific model, the Heisenberg model, in each order of the NLCE with the ones for the finite cluster calculated directly by means of full exact diagonalization. We discuss how to reduce the computational cost of the NLCE calculations by taking into account symmetries and topologies of the linked clusters. Finally, we generalize the algorithm to the thermodynamic limit, and discuss several numerical resummation techniques …


New Bimetallic Iridium Cluster Carbonyl Complexes, Mingwei Chen Jan 2013

New Bimetallic Iridium Cluster Carbonyl Complexes, Mingwei Chen

Theses and Dissertations

Platinum group metal derived bimetallic clusters have been used as precursors to nanoscale catalysts which have been proven to be more effective than their monometallic counterparts. Iridium is a platinum group metal and its applications in catalysis continue to grow. To take advantages of synergies between mixed-metals, we modified iridium clusters with other metal ligands like tin, germanium, and group IB (gold, silver, copper) etc. and obtained a fairly large amount of new iridium derived bimetallic clusters which could be precursors to catalysts with superior properties than that available nowadays. The reaction of Ir4(CO)12 with Ph3SnOH in the presence of …


Asymptotic Behavior Of A T Test Robust To Cluster Heterogeneity, Douglas G. Steigerwald Dec 2012

Asymptotic Behavior Of A T Test Robust To Cluster Heterogeneity, Douglas G. Steigerwald

Douglas G. Steigerwald

We study the behavior of a cluster-robust t statistic and make two principle contributions. First, we relax the restriction of previous asymptotic theory that clusters have identical size, and establish that the cluster-robust t statistic continues to have a Gaussian asymptotic null distribution. Second, we determine how variation in cluster sizes, together with other sources of cluster heterogeneity, affect the behavior of the test statistic. To do so, we determine the sample specific measure of cluster heterogeneity that governs this behavior and show that the measure depends on how three quantities vary over clusters: cluster size, the cluster specific error …