Molecular Orbital Calculations of Water Clusters on Counterpoise-Corrected Potential Energy Surfaces

2004 ◽  
Vol 108 (32) ◽  
pp. 6713-6723 ◽  
Author(s):  
Robert Wieczorek ◽  
Laury Haskamp ◽  
J. J. Dannenberg
Keyword(s):  
Potential Energy ◽  
Molecular Orbital ◽  
Potential Energy Surfaces ◽  
Water Clusters ◽  
Molecular Orbital Calculations ◽  
Energy Surfaces

Resolving the Quadruple Bonding Conundrum in C2 Using Insights Derived from Excited State Potential Energy Surfaces: A Molecular Orbital Perspective

2019 ◽  
Author(s):  
Ishita Bhattacharjee ◽  
Debashree Ghosh ◽  
Ankan Paul
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Molecular Orbital ◽  
High Spin ◽  
Potential Energy Surfaces ◽  
Valence Bond ◽  
Deep Minimum ◽  
State Potential ◽  
Energy Surfaces ◽  
Mo Theory

The question of quadruple bonding in C<sub>2</sub> has emerged as a hot button issue, with opinions sharply divided between the practitioners of Valence Bond (VB) and Molecular Orbital (MO) theory. Here, we have systematically studied the Potential Energy Curves (PECs) of low lying high spin sigma states of C<sub>2</sub>, N<sub>2</sub> and Be<sub>2</sub> and HC≡CH using several MO based techniques such as CASSCF, RASSCF and MRCI. The analyses of the PECs for the<sup> 2S+1</sup>Σ<sub>g/u</sub> (with 2S+1=1,3,5,7,9) states of C<sub>2</sub> and comparisons with those of relevant dimers and the respective wavefunctions were conducted. We contend that unlike in the case of N<sub>2</sub> and HC≡CH, the presence of a deep minimum in the <sup>7</sup>Σ state of C<sub>2</sub> and CN<sup>+</sup> suggest a latent quadruple bonding nature in these two dimers. Hence, we have struck a reconciliatory note between the MO and VB approaches. The evidence provided by us can be experimentally verified, thus providing the window so that the narrative can move beyond theoretical conjectures.

scholarly journals Quantum Mechanistic Studies of the Oxidation of Ethylene by Rhenium Oxo Complexes

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Emmanuel Adu Fosu ◽  
Collins Obuah ◽  
Louis Hamenu ◽  
Albert Aniagyei ◽  
Michael Kojo Ainooson ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Frontier Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Oxo Complexes ◽  
Reaction Energies ◽  
Energy Surfaces ◽  
Rhenium Oxo Complexes ◽  
Epoxidation Catalyst ◽  
Addition Pathway

Transition-metal-mediated oxygen transfer reactions are of importance in both industry and academia; thus, a series of rhenium oxo complexes of the type ReO3L (L = O−, Cl−, F−, OH−, Br−, I−) and their effects as oxidation catalysts on ethylene have been studied. The activation and reaction energies for the addition pathways involving multiple spin states (singlet and triplet) have been computed. In all cases, structures on the singlet potential energy surfaces showed higher stability compared to their counterparts on the triplet potential energy surfaces (PESs). Frontier Molecular Orbital calculations show electrons flow from the HOMO of ethylene to the LUMO of rhenium for all complexes studied except ReO4− where the reverse case occurs. In the reaction between ReO3L (L = O−, Cl−, F−, OH−, Br−, and I−) and ethylene, the concerted [3 + 2] addition pathway on the singlet PES leading to the formation of dioxylate intermediate is favored over the [2 + 2] addition pathway leading to the formation of a metallaoxetane intermediate and subsequent rearrangement to the dioxylate. The activation and the reaction energies for the formation of the dioxylate on the singlet PES for the ligands studied followed the order O− > OH− > I− > F− > Br− > Cl− and O− > OH− > F− > I− > Br− > Cl−, respectively. Furthermore, the activation and the reaction energies for the formation of the metallaoxetane intermediate increase in the order O− > OH− > I− > Br− > Cl− > F− and O− > Br− > I− > Cl− > OH− > F−, respectively. The subsequent rearrangement of the metallaoxetane intermediate to the dioxylate is only feasible in the case of ReO4−. Of all the complexes studied, the best dioxylating catalyst is ReO3Cl (singlet surface) and the best epoxidation catalyst is ReO3F (singlet surface).

Global potential energy surfaces of water clusters; reaction coordinate and annealing analyses

1998 ◽  
Vol 77 (1-3) ◽  
pp. 95-103 ◽  
Author(s):  
Akinori Baba ◽  
Junji Tanaka ◽  
Shinji Saito ◽  
Masakazu Matsumoto ◽  
Iwao Ohmine
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Water Clusters ◽  
Reaction Coordinate ◽  
Energy Surfaces

scholarly journals Quantum Organic Photochemistry. IV. The Photoisomerization of Diimide and Azoalkanes

1973 ◽  
Vol 51 (18) ◽  
pp. 3097-3101 ◽  
Author(s):  
N. Colin Baird ◽  
Jerrald R. Swenson
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Ground State ◽  
Potential Energy Surfaces ◽  
Plane Motion ◽  
Substituent Group ◽  
Significant Barrier ◽  
Energy Surfaces ◽  
Π State

Potential energy surfaces for the isomerization of diimide and azomethane in the ground, 1(n,π*),3 (n,π*), and 3(π,π*) states have been calculated by ab initio molecular orbital methods. Two mechanisms are considered in detail, the first involving in-plane motion of the substituent group and the second involving twisting about the N—N bond. The first mechanism is preferred for the ground and 3(π,π*) states, whereas the second mechanism is preferred for the (n,π*) states. A significant barrier to rotation is predicted for the 3(π,π*) state. The vibrationally-relaxed (twisted) lowest triplet of diimide is predicted to lie 36 kcal mol−1 above the ground state.

Resolving the Quadruple Bonding Conundrum in C2 Using Insights Derived from Excited State Potential Energy Surfaces: A Molecular Orbital Perspective

2019 ◽  
Author(s):  
Ishita Bhattacharjee ◽  
Debashree Ghosh ◽  
Ankan Paul
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Molecular Orbital ◽  
High Spin ◽  
Potential Energy Surfaces ◽  
Valence Bond ◽  
Deep Minimum ◽  
State Potential ◽  
Energy Surfaces ◽  
Mo Theory

The question of quadruple bonding in C<sub>2</sub> has emerged as a hot button issue, with opinions sharply divided between the practitioners of Valence Bond (VB) and Molecular Orbital (MO) theory. Here, we have systematically studied the Potential Energy Curves (PECs) of low lying high spin sigma states of C<sub>2</sub>, N<sub>2</sub> and Be<sub>2</sub> and HC≡CH using several MO based techniques such as CASSCF, RASSCF and MRCI. The analyses of the PECs for the<sup> 2S+1</sup>Σ<sub>g/u</sub> (with 2S+1=1,3,5,7,9) states of C<sub>2</sub> and comparisons with those of relevant dimers and the respective wavefunctions were conducted. We contend that unlike in the case of N<sub>2</sub> and HC≡CH, the presence of a deep minimum in the <sup>7</sup>Σ state of C<sub>2</sub> and CN<sup>+</sup> suggest a latent quadruple bonding nature in these two dimers. Hence, we have struck a reconciliatory note between the MO and VB approaches. The evidence provided by us can be experimentally verified, thus providing the window so that the narrative can move beyond theoretical conjectures.

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