Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation Shell
Small Li<sup>+</sup>Ar<i><sub>n</sub></i> clusters are employed in this work as model systems to study microsolvation. Although first and second solvation shells are expected to be the most relevant ones for this type of atomic solvents, it is also interesting to...
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MDPI AG
2024-02-01
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| Series: | Symmetry |
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| Online Access: | https://www.mdpi.com/2073-8994/16/2/229 |
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| author | Jorge M. C. Marques Frederico V. Prudente |
| author_facet | Jorge M. C. Marques Frederico V. Prudente |
| author_sort | Jorge M. C. Marques |
| collection | DOAJ |
| description | Small Li<sup>+</sup>Ar<i><sub>n</sub></i> clusters are employed in this work as model systems to study microsolvation. Although first and second solvation shells are expected to be the most relevant ones for this type of atomic solvents, it is also interesting to explore larger clusters in order to identify the influence of external atoms on structural and thermodynamic properties. In this work, we perform a global geometry optimization for <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Li</mi><mo>+</mo></msup></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Ar</mi><mi>n</mi></msub></semantics></math></inline-formula> clusters (with <i>n</i> = 41–100) and parallel tempering Monte Carlo (PTMC) simulations for some selected sizes. The results show that global minimum structures of large clusters always have 6 argon atoms in the first solvation shell while maintaining the number of 14 or 16 argon atoms in the second one. By contrast, third and fourth solvation shells vary significantly the number of argon atoms with the cluster size, and other shells can hardly be assigned due to the reduced influence of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Li</mi><mo>+</mo></msup></semantics></math></inline-formula> on the external argon atoms for large clusters. In turn, PTMC calculations show that the melting of the most external solvation shells of large microsolvation clusters occurs at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>T</mi><mo>∼</mo><mn>50</mn><mspace width="0.166667em"></mspace><mi mathvariant="normal">K</mi></mrow></semantics></math></inline-formula>, which is independent of cluster size. Structural transitions can be observed between quasi-degenerated structures at low temperatures. Moreover, the present results highlight the fluxional character of the external solvation shells of these large <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Li</mi><mo>+</mo></msup></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Ar</mi><mi>n</mi></msub></semantics></math></inline-formula> clusters, which may be seen as typical “snowball” structures. |
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| spelling | doaj.art-14ca19b95e994b52b4c10f59e3dba6032024-02-23T15:36:04ZengMDPI AGSymmetry2073-89942024-02-0116222910.3390/sym16020229Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation ShellJorge M. C. Marques0Frederico V. Prudente1CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, PortugalInstituto de Física, Universidade Federal da Bahia, Salvador 40170-115, BA, BrazilSmall Li<sup>+</sup>Ar<i><sub>n</sub></i> clusters are employed in this work as model systems to study microsolvation. Although first and second solvation shells are expected to be the most relevant ones for this type of atomic solvents, it is also interesting to explore larger clusters in order to identify the influence of external atoms on structural and thermodynamic properties. In this work, we perform a global geometry optimization for <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Li</mi><mo>+</mo></msup></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Ar</mi><mi>n</mi></msub></semantics></math></inline-formula> clusters (with <i>n</i> = 41–100) and parallel tempering Monte Carlo (PTMC) simulations for some selected sizes. The results show that global minimum structures of large clusters always have 6 argon atoms in the first solvation shell while maintaining the number of 14 or 16 argon atoms in the second one. By contrast, third and fourth solvation shells vary significantly the number of argon atoms with the cluster size, and other shells can hardly be assigned due to the reduced influence of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Li</mi><mo>+</mo></msup></semantics></math></inline-formula> on the external argon atoms for large clusters. In turn, PTMC calculations show that the melting of the most external solvation shells of large microsolvation clusters occurs at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>T</mi><mo>∼</mo><mn>50</mn><mspace width="0.166667em"></mspace><mi mathvariant="normal">K</mi></mrow></semantics></math></inline-formula>, which is independent of cluster size. Structural transitions can be observed between quasi-degenerated structures at low temperatures. Moreover, the present results highlight the fluxional character of the external solvation shells of these large <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Li</mi><mo>+</mo></msup></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Ar</mi><mi>n</mi></msub></semantics></math></inline-formula> clusters, which may be seen as typical “snowball” structures.https://www.mdpi.com/2073-8994/16/2/229microsolvationparallel tempering Monte Carloglobal optimizationthermodynamic properties |
| spellingShingle | Jorge M. C. Marques Frederico V. Prudente Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation Shell Symmetry microsolvation parallel tempering Monte Carlo global optimization thermodynamic properties |
| title | Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation Shell |
| title_full | Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation Shell |
| title_fullStr | Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation Shell |
| title_full_unstemmed | Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation Shell |
| title_short | Structure and Thermodynamics of Li<sup>+</sup>Ar<i><sub>n</sub></i> Clusters beyond the Second Solvation Shell |
| title_sort | structure and thermodynamics of li sup sup ar i sub n sub i clusters beyond the second solvation shell |
| topic | microsolvation parallel tempering Monte Carlo global optimization thermodynamic properties |
| url | https://www.mdpi.com/2073-8994/16/2/229 |
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