Structures and Energies of SiO<sub>2</sub> Clusters

Harkless, John A. W.; Stillinger, and Dorothea K.; Stillinger, Frank H.

doi:10.1021/jp950807r

Cited by 77 publications

(77 citation statements)

References 18 publications

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“…Also included in the Figure are the 5MR and 6MR structures for the purpose of comparison, as is the point group for each of the structures. From the 13 local minima found in the BOMD simulation, we did not observe any structure with 5-or 6-membered ring, conforming earlier findings [5][6][7][8][9][10] that building blocks of silica nanostructures are indeed 2MR, 3MR, and/or 4MR.…”

Section: Resultssupporting

confidence: 90%

“…[2][3][4] While extensive studies from both experimental and theoretical perspectives have been available, [5][6][7][8][9][10] many questions about their structural and dynamic properties still remain unanswered. For example, how are silica nanowires formed?…”

Section: Introductionmentioning

confidence: 99%

“…Unlike bulk silica, whose building unit is the silicon-centered corner-sharing SiO 4 tetrahedron forming scaffolds in terms of six-membered rings (6MR), silica chains assemble from edge-sharing two-membered rings (2MR), three-member rings (3MR), or four-membered-rings (4MR) terminated at each end by nonbridging oxygen. [5][6][7][8][9][10] These fundamental building blocks of the silica nanostructure can shuffle with each other generating a large number of conformations, many of which can be accessed during the synthetic and dynamic evolution processes.…”

Section: Introductionmentioning

confidence: 99%

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Structural and Dynamic Properties of (SiO₂)₆ Silica Nanostructures: A Quantum Molecular Dynamics Study

2007

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Structural and dynamic properties of the building block of silica nanowires, (SiO 2 ) 6 , are investigated by BornOppenheimer quantum molecular dynamics simulations. Thirteen conformers have been identified, seven of which have not been reported before. The energy component analysis shows that the lower electrostatic interaction differentiates the global minimum from the other structures. We also observe that the maximum hardness principle can be employed to justify the molecular stability for this system. Time profiles of a few density functional reactivity indices exhibit correlations of dynamic fluctuations between HOMO and LUMO and between chemical potential and hardness. Electrophilicity, nucleaofugality, and electrofugality indices are found to change concurrently and significantly, indicating that the nanostructures sampled during the dynamic process are exceedingly reactive and rich in chemistry.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and Dynamic Properties of (SiO₂)₆ Silica Nanostructures: A Quantum Molecular Dynamics Study

2007

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“…Systems, such as isolated SiO 2 , gas-phase oligomers (SiO 2 ) n ͑nр8, nϭ18͒, 10 Si(SiO 2 ) n (nϭ2,3), (SiO 2 ) n (nϭ1 -4), (SiO 2 ) n (n ϭ3 -5), 11 Si 3 O m (mϭ1 -6), 12 Si 2 O 4 2Ϫ , Si 2 O 5 2Ϫ , 13 charged and neutral Si n O m ͑nр6, mр12͒, 14 and (SiO) n (nр5), 15 have been studied using ab initio theories. Information achieved includes geometric structures, energetics, bonding, energy gaps, and valence electronic structures of these species.…”

mentioning

confidence: 99%

High reactivity of silicon suboxide clusters

et al. 2001

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The recent silicon-oxide-assisted formation of Si nanostructures has been studied based on quantummechanical calculations of Si n O m (n,mϭ1 -8) clusters. We found that ͑1͒ energetically the most favorable small silicon-oxide clusters have O atomic ratios at around 0.6, and ͑2͒ remarkably high reactivity at the Si atoms exists in silicon suboxide Si n O m clusters with 2nϾm. The results show that the formation of Si-Si bonds is preferred and thus facilitates the nucleation of Si nanostructures when silicon suboxide clusters come together or stack to a substrate. DOI: 10.1103/PhysRevB.64.113304 PACS number͑s͒: 61.46.ϩw, 73.22.Ϫf Silicon oxide has found important applications in wide fields such as microelectronics, optical communications, and thin-film technology. 1-3 Recent work 4 further showed that silicon oxide could also play an important role in the fabrication of an important nanometer material, the Si nanowire, 5,6 which has attracted much attention for its interesting quantum confinement effect as well as useful electrical, optical, mechanical, and chemical properties. The formation of Si nanowires was achieved by using Si powder sources mixed with SiO 2 . 4 A high yield of nanowires has been obtained when the chemical compositions of Si and O in the source are approximately equal. 7 On the contrary, the important role of oxide is not needed in the conventional growth mechanisms of nanowires. 8,9 To understand the oxide-assisted formation mechanism, the exploration of silicon oxide clusters about their geometric, electronic, and chemical properties would provide useful information.To promote various technological applications based on silicon oxide, theoretical investigations have been performed on small silicon oxide clusters. Systems, such as isolated SiO 2 , gas-phase oligomers (SiO 2 ) n ͑nр8, nϭ18͒, 10 Si(SiO 2 ) n (nϭ2,3), (SiO 2 ) n (nϭ1 -4), (SiO 2 ) n (n ϭ3 -5), 11 Si 3 O m (mϭ1 -6), 12 Si 2 O 4 2Ϫ , Si 2 O 5 2Ϫ , 13 charged and neutral Si n O m ͑nр6, mр12͒, 14 and (SiO) n (nр5), 15 have been studied using ab initio theories. Information achieved includes geometric structures, energetics, bonding, energy gaps, and valence electronic structures of these species. However, understanding of the oxide-assisted formation of Si nanowires in which silicon oxide acts as a special ''catalyst'' would require a systematic study of Si n O m . In this work, we have made such a systematic study of Si n O m (n,mϭ1 -8) at the quantum-mechanical level, aiming at elucidating the oxide-assisted formation mechanism of silicon nanowires.Energetically, the more favorable structure has been searched for each composition of Si n O m (n,mϭ1 -8) by means of calculations with density functional theory ͑DFT͒. The DFT calculations in this work used the popular B3LYP method, which is based on the Becke-type three-parameter density functional theory. 16 An economic basis set, where 3-21G and 6-31G* were selected to describe Si and O, respectively, according to their electronegativities and charge transfers, 17 was used in ...

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“…In our calculation, the silica cluster is modeled by the TTAM potential. 18 Because the TTAM potential was developed for the condensed phase siliceous materials, the use of such potential to describe the structure of silica cluster is an approximation, which means that the lowest energy structure we obtained by GA is probably incorrect. For example, the lowest energy structure of the tetramer (SiO 2 ) 4 given by our GA with TTAM potential is a 3D cage structure (see Fig.…”

Section: Theoreticalmentioning

confidence: 99%

Magic number silicon dioxide‐based clusters: Laser ablation‐mass spectrometric and density functional theory studies

Kong¹,

Zhao²,

Wang³

et al. 2005

J Comput Chem

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The magic number silica clusters [(SiO(2))(n)O(2)H(3)](-) with n = 4 and 8 have been observed in the XeCl excimer laser (308 nm) ablation of various porous siliceous materials. The structural origin of the magic number clusters has been studied by the density functional theoretical calculation at the B3LYP/6-31G** level, with a genetic algorithm as a supplementary tool for global structure searching. The DFT results of the first magic number cluster are parallel to the corresponding Hartree-Fock results previously reported with only small differences in the structural parameters. Theoretical calculation predicts that the first magic number cluster (SiO(2))(4)O(2)H(4) and its anion [(SiO(2))(4)O(2)H(3)](-) will most probably take pseudotetrahedral cage-like structures. To study the structural properties of the second magic number cluster, geometries of the bare cluster (SiO(2))(8), the neutral complex cluster (SiO(2))(8)O(2)H(4), and the anionic cluster [(SiO(2))(8)O(2)H(3)](-) are fully optimized at the B3LYP/6-31G** level, and the corresponding vibrational frequencies are calculated. The DFT calculations predict that the ground state of the bare silica octamer (SiO(2))(8) has a linear chain structure, whereas the second magic number complex cluster (SiO(2))(8)O(2)H(4) and its anion [(SiO(2))(8)O(2)H(3)](-) are most probably a mixture of cubic cage-like structural isomers with an O atom inside the cage and several quasi-bicage isomers with high intercage interactions. The stabilization of these structures can also be attributed to the active participation of the group of atoms 2O and 4H (3H for the anion) in chemical bonding during cluster formation. Our theoretical calculation gives preliminary structural interpretation of the presence of the first and second magic number clusters and the absence of higher magic numbers.

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Structures and Energies of SiO₂ Clusters

Cited by 77 publications

References 18 publications

Structural and Dynamic Properties of (SiO₂)₆ Silica Nanostructures: A Quantum Molecular Dynamics Study

Structural and Dynamic Properties of (SiO₂)₆ Silica Nanostructures: A Quantum Molecular Dynamics Study

High reactivity of silicon suboxide clusters

Magic number silicon dioxide‐based clusters: Laser ablation‐mass spectrometric and density functional theory studies

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Structures and Energies of SiO2 Clusters

Cited by 77 publications

References 18 publications

Structural and Dynamic Properties of (SiO2)6 Silica Nanostructures: A Quantum Molecular Dynamics Study

Structural and Dynamic Properties of (SiO2)6 Silica Nanostructures: A Quantum Molecular Dynamics Study

High reactivity of silicon suboxide clusters

Magic number silicon dioxide‐based clusters: Laser ablation‐mass spectrometric and density functional theory studies

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Structures and Energies of SiO₂ Clusters

Structural and Dynamic Properties of (SiO₂)₆ Silica Nanostructures: A Quantum Molecular Dynamics Study

Structural and Dynamic Properties of (SiO₂)₆ Silica Nanostructures: A Quantum Molecular Dynamics Study