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dc.contributor.authorBosá, Ivana.en_US
dc.date.accessioned2009-07-14T19:41:48Z
dc.date.available2009-07-14T19:41:48Z
dc.date.issued2004-07-14T19:41:48Z
dc.identifier.urihttp://hdl.handle.net/10464/2303
dc.description.abstractOur 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.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectMonte Carlo method.en_US
dc.subjectExpectation-maximization algorithms.en_US
dc.subjectParticles (Nuclear physics)en_US
dc.titleExact property estimation from diffusion Monte Carlo with minimal stochastic reconfiguration /en_US
dc.typeElectronic Thesis or Dissertationen_US
dc.degree.nameM.Sc. Earth Sciencesen_US
dc.degree.levelMastersen_US
dc.contributor.departmentDepartment of Earth Sciencesen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US


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