Excited interatomic potential energy surfaces of Rb + He that correlate with Rb terms 52S through 72S

2018 ◽  
Vol 20 (46) ◽  
pp. 29274-29284 ◽  
Author(s):  
Amit R. Sharma ◽  
David E. Weeks
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Configuration Interaction ◽  
Potential Energy Surfaces ◽  
Interatomic Potential ◽  
Basis Sets ◽  
Spin Orbit ◽  
State Spin ◽  
Energy Surfaces ◽  
Quadruple Zeta

The excited state, spin-free, and spin–orbit interatomic potential energy surfaces of Rb + He which correlate with the Rb atomic terms 52S, 52P, 42D, 62S, 62P, 52D, and 72S, are calculated at multi-reference configuration interaction level of theory using all-electron basis sets of triple and quadruple-zeta quality that have been contracted for Douglas–Kroll–Hess (DKH) Hamiltonian and includes core-valence correlation. Important features of the potential energy surfaces are discussed with implications for alkali laser spectroscopy.

Features of the thioformaldehyde potential energy surfaces

1985 ◽  
Vol 63 (7) ◽  
pp. 1910-1917 ◽  
Author(s):  
John D. Goddard
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
Configuration Interaction ◽  
Potential Energy Surfaces ◽  
Transition States ◽  
Basis Sets ◽  
Dissociation Limit ◽  
Molecular Dissociation ◽  
Energy Surfaces ◽  
Higher Excited States

The structures of seven minima and five transition states of the S0 and T1 potential energy surfaces of thioformaldehyde have been located at the 3-21G* SCF level. Further calculations have been carried out to determine harmonic vibrational frequencies and to examine the effects of larger basis sets and of configuration interaction on energy differences. The molecular dissociation limit of H2 and CS is thermodynamically accessible at the energy of the lowest n,π* excited states and the singlet thiohydroxymethylenes lie only slightly too high. However, there are large barriers of ~85 to 90 kcal mol−1 to the molecular dissociation or to the 1,2-hydrogen shifts from thioformaldehyde to the thiohydroxymethylenes. The dissociation to H and HCS requires ~85.4 kcal mol−1 on the ground singlet and faces a barrier of several kcal mol−1 relative to products on the triplet surface. Any unimolecular photochemistry of thioformaldehyde is likely to require excitation to higher excited states than the lowest n,π* states.

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.

Accuracy of Coupled Cluster Excited State Potential Energy Surfaces

2018 ◽  
Vol 14 (11) ◽  
pp. 5859-5869 ◽  
Author(s):  
Attila Tajti ◽  
John F. Stanton ◽  
Devin A. Matthews ◽  
Péter G. Szalay
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Coupled Cluster ◽  
State Potential ◽  
Energy Surfaces
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