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Full-Text Articles in Physics
Understanding Three-Body Interactions In Hexagonal Close Packed Solid He-4, Ashleigh Locke Barnes
Understanding Three-Body Interactions In Hexagonal Close Packed Solid He-4, Ashleigh Locke Barnes
Doctoral Dissertations
The ground state properties of hexagonal close packed (hcp) solid 4He [He-4] are dominated by large atomic zero point motions which make the primary contribution to the solid’s low-temperature Debye-Waller (DW) factors. Preliminary investigations have also suggested that three-body interactions can play an important role in this system, particularly at higher densities. However, due to their computational cost, these interactions are not generally incorporated into theoretical models of solid 4He [He-4]. In order to accurately treat both zero point motion and three-body interactions, we have developed a perturbative treatment in which the three-body energy is added as a …
Population Size Bias In Descendant-Weighted Diffusion Quantum Monte Carlo Simulations, G. Lee Warren, Robert J. Hinde
Population Size Bias In Descendant-Weighted Diffusion Quantum Monte Carlo Simulations, G. Lee Warren, Robert J. Hinde
Chemistry Publications and Other Works
We consider the influence of population size on the accuracy of diffusion quantum Monte Carlo simulations that employ descendant weighting or forward walking techniques to compute expectation values of observables that do not commute with the Hamiltonian. We show that for a simple model system, the d-dimensional isotropic harmonic oscillator, the population size must increase rapidly with d in order to ensure that the simulations produce accurate results. When the population size is too small, expectation values computed using descendant-weighted diffusion quantum Monte Carlo simulations exhibit significant systematic biases.
Population Size Bias In Descendant-Weighted Diffusion Quantum Monte Carlo Simulations, G. Lee Warren, Robert Hinde
Population Size Bias In Descendant-Weighted Diffusion Quantum Monte Carlo Simulations, G. Lee Warren, Robert Hinde
Robert Hinde
We consider the influence of population size on the accuracy of diffusion quantum Monte Carlo simulations that employ descendant weighting or forward walking techniques to compute expectation values of observables that do not commute with the Hamiltonian. We show that for a simple model system, the d-dimensional isotropic harmonic oscillator, the population size must increase rapidly with d in order to ensure that the simulations produce accurate results. When the population size is too small, expectation values computed using descendant-weighted diffusion quantum Monte Carlo simulations exhibit significant systematic biases.