On the Structure of Boat-Shaped Hexalead(II) Cations with OH Bridges

2004 ◽  
Vol 69 (11) ◽  
pp. 2055-2067 ◽  
Author(s):  
Martin Breza ◽  
Stanislav Biskupič
Keyword(s):  
Electronic Structures ◽  
Water Solutions ◽  
Hartree Fock ◽  
Total Charges

Using Hartree-Fock, B3LYP, and MP2 treatments, the optimal boat-shaped geometries and corresponding electronic structures of [Pb6Om(μ3-OH)n]q complex cations with total charges q = 12 - 2m - n, m = 0 or 1, n = 6 or 8, are investigated. Whereas the [Pb6(μ3-OH)6]6+ cation is unstable, the remaining structures preserve C2v symmetry. Direct Pb-Pb interactions are weakly antibonding in all the systems under study. The clusters are held together exclusively by relatively weak Pb-O bonds. The effects of central O and two additional μ3-OH bridges in [Pb6O(μ3-OH)8]2+ are not fully cooperative. [Pb6O(μ3-OH)6]4+ and [Pb6(μ3-OH)8]4+ may coexist in water solutions in comparable concentrations.

On the Stability of Hydroxo-Dilead(II) Complex Cations

2003 ◽  
Vol 68 (12) ◽  
pp. 2377-2385 ◽  
Author(s):  
Martin Breza ◽  
Stanislav Biskupič
Keyword(s):  
Aqueous Solutions ◽  
Electronic Structures ◽  
Hartree Fock ◽  
The Stability ◽  
Total Charges

Using Hartree-Fock, B3LYP and MP2 treatments, the optimal geometries and corresponding electronic structures of various isomers of [Pb2(OH)n]q complex cations with total charges q = 4 - n, n = 1, 2, 3, are investigated. [Pb(μ-OH)Pb]3+ seems to be the most stable whereas [Pb(μ-OH)Pb(OH)]2+ and [Pb(μ-OH)Pb(OH)2]+ are unstable (because additional non-bridging hydroxyl weakens the neighboring Pb-Oμ and Oμ-Hμ bonds). Direct Pb-Pb and Oμ-Oμ interactions are weakly antibonding in all the systems under study. The clusters are held together exclusively by relatively weak Pb-O bonds. Non-measurable concentrations of [Pb(μ-OH)Pb]3+ in aqueous solutions might be explained by its reaction with OH- yielding preferably unstable [Pb(μ-OH)Pb(OH)]2+ species.

On the Structure of Tetralead(II) Complexes with OH Bridges

2004 ◽  
Vol 69 (11) ◽  
pp. 2045-2054 ◽  
Author(s):  
Martin Breza ◽  
Stanislav Biskupič
Keyword(s):  
Oxygen Atom ◽  
Electronic Structures ◽  
Apical Position ◽  
Hartree Fock ◽  
Central Oxygen ◽  
Total Charges

Using Hartree-Fock, B3LYP and MP2 treatments, the optimal geometries and corresponding electronic structures of tetrahedral [Pb4(μ3-OH)n]q and [Pb4O(μ3-OH)n]q-2 complex cations with total charges q = 8 - n , n = 2, 3, 4, are investigated. After OH- removal, the central oxygen atom in [Pb4O(μ3-OH)4]2+ is shifted to the apical position in [Pb4O(μ3-OH)3]3+ whereas the [Pb4(μ3-OH)2]6+ and [Pb4O(μ3-OH)2]4+ complex cations are unstable. Direct Pb-Pb and O-O interactions are weakly antibonding in all the systems under study. The clusters are held together exclusively by relatively weak Pb-O bonds. A higher stability of the complex cations with a larger number of OH- bridges may be confirmed.

scholarly journals On topological materials as photocatalysts for water splitting by visible light

2021 ◽  
Author(s):  
Ahmad Ranjbar ◽  
Hossein Mirhosseini ◽  
Thomas D Küehne
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Water Oxidation ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Edge ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Hartree Fock ◽  
Topological Materials

Abstract We performed virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated by means of hybrid density functional theory including exact Hartree-Fock exchange. Our final list contains materials which have band gaps between 1.0 eV and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes.

Topological methods of quantum chemistry for a study of chemical reactivity

1980 ◽  
Vol 45 (9) ◽  
pp. 2452-2462 ◽  
Author(s):  
Jiří Pancíř
Keyword(s):  
Electronic Structures ◽  
Chemical Reactivity ◽  
Average Error ◽  
Medium Size ◽  
Electron Pairs ◽  
Hartree Fock ◽  
Structural Formulas ◽  
Quantum Chemical Model ◽  
Core Electrons ◽  
The One

In this paper all approximations are discussed which lead to a quantum chemical model which is adequate for structural formulas known in classical organic chemistry. Neglect of the energy differences caused by changes of valence and dihedral angles, i.e. neglect of all nonbonding interactions, leads to the separation of the Hartree-Fock matrix in blocks of core electrons, nonbonding electron pairs, two center blocks of σ-bonds and delocalized π-electronic structures. Such a procedure can be formulated at all levels of sophistication - from the one electron approximation to the MC-SCF method. Even on the one electron level, the average error in heats of atomization (35.9 kJ/mol) is lower than that of the more complicated geometrical methods MINDO/3 (52.1 kJ/mol) and MNDO (39.6 kJ/mol). The procedure suggested is about two orders of magnitude more efficient than geometrical ones of the same level and can be, therefore, used for a study of reaction mechanisms of medium size systems (30-50 atoms) without large expense.

The Mechanism of Slow Component Suppression in Lanthanum Doped Barium Fluoride Crystal

1994 ◽  
Vol 348 ◽  
Author(s):  
Gu Mu ◽  
Chen Lingyan ◽  
Li Qing ◽  
Wang Liming ◽  
Xiang Kaihua
Keyword(s):  
Electronic Structures ◽  
Cluster Model ◽  
Local Density ◽  
Slow Component ◽  
Barium Fluoride ◽  
Molecular Cluster ◽  
Entire System ◽  
Scintillation Light ◽  
Hartree Fock ◽  
Self Consistent

ABSTRACTThe electronic structures of pure BaF2 crystal and lanthanum doped BaF2 crystal have been calculated in a self-consistent molecular-cluster model. The cluster is embedded in the crystal lattice and the entire system treatediteratively in the Hartree-Fock-Slater local-density theory. As lanthanum doped BaF2 is concerned, the obtained results revealed that the F1–i which is introduced by the lanthanum may contribute to the suppression ofthe slow component in the scintillation light of BaF2 crystal.

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