Macià Escatlla, A;
Lazauskas, T;
Woodley, SM;
Bromley, ST;
(2019)
Structure and Properties of Nanosilicates with Olivine (Mg₂Si2O₄)N and Pyroxene (MgSiO₃)N Compositions.
ACS Earth and Space Chemistry
10.1021/acsearthspacechem.9b00139.
(In press).
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Abstract
Magnesium-rich silicates are ubiquitous both terrestrially and astronomically, where they are often present as small particles. Nanosized Mg-rich silicate particles are likely to be particularly important for understanding the formation, processing, and properties of cosmic dust grains. Although astronomical observations and laboratory studies have revealed much about such silicate dust, our knowledge of this hugely important class of nanosolids largely rests on top-down comparisons with the properties of bulk silicates. Herein, we provide a foundational bottom-up study of the structure and properties of Mg-rich nanosilicates based on carefully procured atomistic models. Specifically, we employ state-of-the-art global optimization methods to search for the most stable structures of silicate nanoclusters with olivine (Mg_{2}SiO{4})_{N} and pyroxene (MgSiO_{3})_{N} compositions with N = 1–10. To ensure the reliability of our searches, we develop a new interatomic potential that has been especially tuned for nanosilicates. Subsequently, we refine these searches and calculate a range of physicochemical properties of the most stable nanoclusters using accurate density functional theory based electronic structure calculations. We report a detailed analysis of structural and energy properties, charge distributions, and infrared vibrational spectra, where in all cases we compare our finding for nanosilicates with those of the corresponding bulk silicate crystals. For most properties considered, we find large differences with respect to the bulk limit, underlining the limitations of a top-down approach for describing these species. Overall, our work provides a new platform for an accurate and detailed understanding of nanoscale silicates.
| Type: | Article |
|---|---|
| Title: | Structure and Properties of Nanosilicates with Olivine (Mg₂Si2O₄)N and Pyroxene (MgSiO₃)N Compositions |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/acsearthspacechem.9b00139 |
| Publisher version: | https://doi.org/10.1021/acsearthspacechem.9b00139 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | cosmic dust grains, silicates, infrared spectra, nanoclusters, interstellar medium, computational modeling, global optimization, density functional theory |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10078876 |
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