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Exact property estimation from diffusion Monte Carlo with minimal stochastic reconfiguration /

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Show simple item record Bosá, Ivana. en_US 2009-07-14T19:41:48Z 2009-07-14T19:41:48Z 2004-07-14T19:41:48Z
dc.description.abstract Our objective is to develop a diffusion Monte Carlo (DMC) algorithm to estimate the exact expectation values, ($o|^|^o), of multiplicative operators, such as polarizabilities and high-order hyperpolarizabilities, for isolated atoms and molecules. The existing forward-walking pure diffusion Monte Carlo (FW-PDMC) algorithm which attempts this has a serious bias. On the other hand, the DMC algorithm with minimal stochastic reconfiguration provides unbiased estimates of the energies, but the expectation values ($o|^|^) are contaminated by ^, an user specified, approximate wave function, when A does not commute with the Hamiltonian. We modified the latter algorithm to obtain the exact expectation values for these operators, while at the same time eliminating the bias. To compare the efficiency of FW-PDMC and the modified DMC algorithms we calculated simple properties of the H atom, such as various functions of coordinates and polarizabilities. Using three non-exact wave functions, one of moderate quality and the others very crude, in each case the results are within statistical error of the exact values. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Monte Carlo method. en_US
dc.subject Expectation-maximization algorithms. en_US
dc.subject Particles (Nuclear physics) en_US
dc.title Exact property estimation from diffusion Monte Carlo with minimal stochastic reconfiguration / en_US
dc.type Electronic Thesis or Dissertation en_US M.Sc. Earth Sciences en_US Masters en_US
dc.contributor.department Department of Earth Sciences en_US Faculty of Mathematics and Science en_US

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