Structures and Energetics of (MgCO _{3} ) _{n} Clusters ( n ≤ 16)
Abstract
There is significant interest in the role of carbonate minerals for the storage of CO _{2} and the role of prenucleation dusters in their formation. Global minima for (MgCO _{3}) _{n} (n ≤ 16) structures were optimized using a tree growthhybrid genetic algorithm in conjunction with MNDO/MNDO/d semiempirical molecular orbital calculations followed by density functional theory geometry optimizations with the B3LYP functional. The most stable isomers for (MgCO _{3}) _{n} (n < 5) are approximately 2dimensional. Mg can be bonded to one or two 0 atoms of a CO _{3} ^{2}, and the 1O bonding scheme is more favored as the cluster becomes larger. The average CMg coordination number increases as the cluster size increases, and at n = 16, the average CMg coordination number was calculated to be 5.2. The normalized dissociation energy to form monomers increases as n increases. At n = 16, the normalized dissociation energy is calculated to be 116.2 kcal/mol, as compared to the bulk value of 153.9 kcal/mol. The adiabatic reaction energies for the recombination reactions of (MgO) _{n}clusters and CO _{2} to form (MgCO _{3}) _{n} were calculated. The exothermicity of the normalized recombination energy < RE >(CO _{2}) decreases as n increasesmore »
 Authors:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences
 Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Chemistry
 Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC22)
 OSTI Identifier:
 1261428
 Grant/Contract Number:
 AC0500OR22725
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
 Additional Journal Information:
 Journal Volume: 119; Journal Issue: 14; Journal ID: ISSN 10895639
 Publisher:
 American Chemical Society
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Citation Formats
Chen, Mingyang, Jackson, Virgil E., Felmy, Andrew R., and Dixon, David A. Structures and Energetics of (MgCO3 )n Clusters ( n ≤ 16). United States: N. p., 2015.
Web. doi:10.1021/jp511823k.
Chen, Mingyang, Jackson, Virgil E., Felmy, Andrew R., & Dixon, David A. Structures and Energetics of (MgCO3 )n Clusters ( n ≤ 16). United States. doi:10.1021/jp511823k.
Chen, Mingyang, Jackson, Virgil E., Felmy, Andrew R., and Dixon, David A. 2015.
"Structures and Energetics of (MgCO3 )n Clusters ( n ≤ 16)". United States.
doi:10.1021/jp511823k. https://www.osti.gov/servlets/purl/1261428.
@article{osti_1261428,
title = {Structures and Energetics of (MgCO3 )n Clusters ( n ≤ 16)},
author = {Chen, Mingyang and Jackson, Virgil E. and Felmy, Andrew R. and Dixon, David A.},
abstractNote = {There is significant interest in the role of carbonate minerals for the storage of CO2 and the role of prenucleation dusters in their formation. Global minima for (MgCO3)n (n ≤ 16) structures were optimized using a tree growthhybrid genetic algorithm in conjunction with MNDO/MNDO/d semiempirical molecular orbital calculations followed by density functional theory geometry optimizations with the B3LYP functional. The most stable isomers for (MgCO3)n (n < 5) are approximately 2dimensional. Mg can be bonded to one or two 0 atoms of a CO32, and the 1O bonding scheme is more favored as the cluster becomes larger. The average CMg coordination number increases as the cluster size increases, and at n = 16, the average CMg coordination number was calculated to be 5.2. The normalized dissociation energy to form monomers increases as n increases. At n = 16, the normalized dissociation energy is calculated to be 116.2 kcal/mol, as compared to the bulk value of 153.9 kcal/mol. The adiabatic reaction energies for the recombination reactions of (MgO)nclusters and CO2 to form (MgCO3)n were calculated. The exothermicity of the normalized recombination energy < RE >(CO2) decreases as n increases and converged to the experimental bulk limit rapidly. The normalized recombination energy < RE >(CO2) was calculated to be 52.2 kcal/mol for the monomer and 30.7 kcal/mol for n = 16, as compared to the experimental value of 27.9 kcal/mol for the solid phase reaction. Infrared spectra for the lowest energy isomers were calculated, and absorption bands in the previous experimental infrared studies were assigned with our density functional theory predictions. The 13C, 17O, and 25Mg NMR chemical shifts for the clusters were predicted. We found that the results provide insights into the structural and energetic transitions from nanoclusters of (MgCO3)n to the bulk and the spectroscopic properties of clusters for their experimental identification.},
doi = {10.1021/jp511823k},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 14,
volume = 119,
place = {United States},
year = 2015,
month = 3
}
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