2026-09-23T19:43:35Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/18880 2023-07-10 col_2142_8859 col_2142_5131 com_2142_8858 com_2142_234 com_2142_5130

3644331 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-04-26T16:48:37Z Item is restricted indefinitely. Thesis Martin, Richard M. Natoli, Vincent Dominic 2011-04-26T16:48:36Z 2011-04-26T16:48:36Z 10000-01-01 1994 Variational and Diffusion Monte Carlo are powerful computational methods which can afford accurate estimates of the ground state properties of quantum many-body problems. We have applied these Monte Carlo methods to the high pressure phases of solid hydrogen to elucidate those parts of the phase diagram where experimental results are inconclusive or lacking. The method allows us to treat both electrons and protons as quantum particles by incorporating them in the trial wavefunction and avoids the Born-Oppenheimer and harmonic approximations. Our trial wavefunction uses single-body solutions from a meanfield calculation coupled with standard pair potential terms to achieve the most accurate results to date. Equally accurate results were realized for calculations in the disparate insulating molecular and metallic atomic regime. We performed a study of the possible ground state structures of the atomic metallic phase of hydrogen which identifies a new family of low energy atomic structures. Another study was done on the molecular phase over the range of pressures( 40-180GPa) where recent experiments have observed spectral discontinuities and other interesting new phenomena. Particular attention was directed to determining the equation of state and orientational ordering. We find that molecular hydrogen adopts a lower symmetry insulating structure over a wide range of pressure. The results of the atomic and molecular studies are combined to draw conclusions about the molecular-atomic transition and other details about the high pressure phase diagram. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-04-26T16:48:36Z No. of bitstreams: 1 1994_Natoli.pdf: 2067168 bytes, checksum: 78e7ee4d34074e46b60ec062f98be19d (MD5) Made available in DSpace on 2011-04-26T16:48:36Z (GMT). No. of bitstreams: 1 1994_Natoli.pdf: 2067168 bytes, checksum: 78e7ee4d34074e46b60ec062f98be19d (MD5) Previous issue date: 1994 Restriction data tranferred 2014-07-01T11:12:15-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis U of I Only http://hdl.handle.net/2142/18880 en 1994 Vincent Dominic Natoli Diffusion Monte Carlo (DMC) Variation Monte Carlo computational physics high pressure high pressure phases solid hydrogen hydrogen quantum physics A quantum Monte Carlo study of the high pressure phases of solid hydrogen Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.