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Ceperley, David M. Grossman, Jeffrey Curtis 2011-04-20T20:14:01Z 2011-04-20T20:14:01Z 10000-01-01 1996 The goals of our research have been to: (i) expand the applicability of the quantum Monte Carlo (QMC) methods to larger molecular systems and check the reliability of traditional approaches, (ii) determine the impact of correlation energy on a variety of systems in which correlation is important, (iii) investigate new silicon clusters which may generate unique materials, (iv) determine the most stable C10 and C2o clusters, (v) achieve kcal/mol accuracy for molecular reactions, and (vi) develop the QMC methodology by improving the QMC trial functions. In order to attain these goals, we have unambiguosly determined the role of correlation energy in silicon and carbon systems, calculated binding energies, barrier heights, heats of formation, and electron affinities for selected molecular systems with high accuracy, and gauged the performance and predictability of more than ten standard methods. We have also shown that the utilization of natural orbitals leads to a significant improvement in the quality of the trial wavefunctions. We demonstrate that, through a combination of advances in both accuracy and scaling, QMC is a highly attractive alternative to the traditional methods, and for some cases it appears to be the only currently available approach to provide parameter-free predictions for energies of systems with more than 40 electrons. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-04-20T20:14:01Z No. of bitstreams: 1 1996_grossman.pdf: 3797892 bytes, checksum: 193d3b1b64e18ca74eb5f42c34c22df2 (MD5) Made available in DSpace on 2011-04-20T20:14:01Z (GMT). No. of bitstreams: 1 1996_grossman.pdf: 3797892 bytes, checksum: 193d3b1b64e18ca74eb5f42c34c22df2 (MD5) Previous issue date: 1996 Restriction data tranferred 2014-07-01T11:12:08-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-04-20T20:14:01Z Item is restricted indefinitely. Thesis U of I Only 4011030 http://hdl.handle.net/2142/18852 en 1996 Jeffrey Curtis Grossman quantum Monte Carlo (QMC) correlation energy silicon clusters molecular systems Quantum Monte Carlo methods for molecular systems: New developments and applications Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.