Browsing by Author "Modisette, Jason Perry"

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    A theoretical study of cyanide on alkali-halide and alkali-metal surfaces using density functional theory
    (1995) Modisette, Jason Perry; Nordlander, Peter J.
    Many interesting physical phenomena have been observed in electron-stimulated desorption studies of the cyanide molecule on alkali halide and alkali metal surfaces. We have performed a theoretical investigation of the nature of the cyanide-surface bond and of the desorption process using an ab initio density functional theoretic method of calculating electronic structure in the local density and Born-Oppenheimer approximations. We compare our results with experiment, and offer an explanation for an anomalous non-Boltzmann, temperature-independent rotational distribution experimentally observed in cyanide desorbed from these surfaces. As a verification of the method, we have performed extensive calculations on different bare alkali halide and alkali metal clusters and compared them with experimental results.
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    Wavelets in electronic structure calculations
    (1997) Modisette, Jason Perry; Nordlander, Peter J.
    Ab initio calculations of the electronic structure of bulk materials and large clusters are not possible on today's computers using current techniques. The storage and diagonalization of the Hamiltonian matrix are the limiting factors in both memory and execution time. The scaling of both quantities with problem size can be reduced by using approximate diagonalization or direct minimization of the total energy with respect to the density matrix in conjunction with a localized basis. Wavelet basis members are much more localized than conventional bases such as Gaussians or numerical atomic orbitals. This localization leads to sparse matrices of the operators that arise in SCF multi-electron calculations. We have investigated the construction of the one-electron Hamiltonian, and also the effective one-electron Hamiltonians that appear in density-functional and Hartree-Fock theories. We develop efficient methods for the generation of the kinetic energy and potential matrices, the Hartree and exchange potentials, and the local exchange-correlation potential of the LDA. Test calculations are performed on one-electron problems with a variety of potentials in one and three dimensions.