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6. Applications: The Chemical Industry

Author

Chaka, Anne M., Westmoreland, Phillip R., Kollman, Peter A., Chaka, Anne M., Cummings, Peter T., Morokuma, Keiji, Neurock, Matthew, Stechel, Ellen B., and Vashishta, Priya

Published
2002
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16. Structure of cis,trans-1,4-difluorobutadiene from microwave spectroscopy

Author

Craig, Norman C., Oertel, Catherine M., Oertel, David C., Tubergen, Michael J., Lavrich, Richard J., and Chaka, Anne M.

Subjects
Chemistry, Physical and theoretical -- Research, Butadiene -- Physiological aspects, Fluorine -- Physiological aspects, Microwave spectroscopy -- Usage, Deuterium -- Physiological aspects, Chemicals, plastics and rubber industries
Published
2002

22. Applying Molecular and Materials Modeling

Author

Westmoreland, Phillip R., primary, Kollman, Peter A., additional, Chaka, Anne M., additional, Cummings, Peter T., additional, Morokuma, Keiji, additional, Neurock, Matthew, additional, Stechel, Ellen B., additional, and Vashishta, Priya, additional

Published
2002
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39. Ab Initio Thermodynamics and the Relationship between Octahedral Distortion, Lattice Structure, and Proton Substitution Defects in Malachite/Rosasite Group Endmember Pokrovskite Mg2CO3(OH)2.

Author

Chaka, Anne M.

Subjects
*THERMODYNAMICS, *CRYSTAL lattices, *CRYSTAL structure, *CARBONATES, *SUBSTITUTION reactions, *MALACHITE, *NANOELECTRONICS
Abstract

Divalent metal hydroxycarbonates with M2CO3(OH)2 stoichiometry are widely used in industry and are abundant in nature as the malachite/rosasite group of minerals. Essential to their performance as catalytic precursors and in nanoelectronics, these materials and minerals exhibit a high degree of cation ordering in mixed metal systems due to differences in distortion of the octahedral metal sites. Density-functional theory (DFT) calculations on pokrovskite Mg2CO3(OH)2 in the rosasite structure and Mg analogues of monoclinic and orthorhombic forms of malachite determine that the octahedral sites are innately distorted, and that d9 Cu(II) Jahn-Teller distortion accommodates this distortion rather than causes it, leading to the significant preference of Cu for the type I octahedral sites. This distortion also leads to a high propensity for formation of cation vacancies charge balanced by proton substitution. Ab initio thermodynamics is used to determine that there are conditions under which proton substitution defects are slightly more stable than the stoichiometric structure, consistent with the widespread observation of such defects in pokrovskite in nature. Pokrovskite itself is most likely to form under CO2-rich/low water conditions, particularly those utilizing supercritical CO2 for carbon sequestration and is sufficiently thermodynamically stable to trap CO2 under geological conditions. Low temperature and high water concentration promotes the formation of proton substitution defects, which has implications for synthesis of any material where octahedral strain may be relieved by proton substitution defects. [ABSTRACT FROM AUTHOR]

Published
2016
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49. Applications of Molecular and Materials Modeling

Author

LOYOLA COLL BALTIMORE MD INTERNATIONAL TECHNOLOGY RESEARCH INST, Westmoreland, Phillip R., Kollman, Peter A., Chaka, Anne M., Cummings, Peter T., Morokuma, Keiji, Neurock, Matthew, Stechel, Ellen B., Vashishta, Priya, LOYOLA COLL BALTIMORE MD INTERNATIONAL TECHNOLOGY RESEARCH INST, Westmoreland, Phillip R., Kollman, Peter A., Chaka, Anne M., Cummings, Peter T., Morokuma, Keiji, Neurock, Matthew, Stechel, Ellen B., and Vashishta, Priya

Abstract

This report reviews the development and applications of molecular and materials modeling in Europe and Japan in comparison to those in the United States. Topics covered include computational quantum chemistry, molecular simulations by molecular dynamics and Monte Carlo methods, mesoscale modeling of material domains, molecular-structure/macroscale property correlations like QSARs and QSPRs, and related information technologies like informatics and special-purpose molecular-modeling computers. The panel's findings include the following: The United States leads this field in many scientific areas. However, Canada has particular strengths in DFT methods and homogeneous catalysis; Europe in heterogeneous catalysis, mesoscale, and materials modeling; and Japan in materials modeling and special-purpose computing. Major government-industry initiatives are underway in Europe and Japan, notably in multi-scale materials modeling and in development of chemistry-capable ab-initio molecular dynamics codes. In European and U.S. assessments of nanotechnology, it was also concluded that to advance the field most quickly and competitively the need is acute for applying new and existing methods of molecularly based modeling. Additional findings are outlined in the panel's executive summary., The original document contains color images.

Published
2002

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