Quasi-One-Dimensional Correlated Electronic Materials

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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. ***