A comparative study of the energetics, structures, and mechanisms of the HCN ↔ HNC and LiCN ↔ LiNC isomerizations

1996 ◽  
Vol 74 (6) ◽  
pp. 1072-1077 ◽  
Author(s):  
V. Sreedhara Rao ◽  
Amrendra Vijay ◽  
A.K. Chandra
Keyword(s):  
Potential Energy ◽  
Electron Correlation ◽  
Potential Energy Surfaces ◽  
Basis Sets ◽  
Ab Initio Theory ◽  
Molecular Bond ◽  
Bond Rearrangement ◽  
Energy Surfaces ◽  
Isomerization Processes ◽  
Rearrangement Processes

The potential energy surfaces of the HCN ↔ HNC and LiCN ↔ LiNC isomerization processes were determined by ab initio theory using fully optimized triple-zeta double polarization types of basis sets. Both the MP2 corrections and the QCISD level of calculations were performed to correct for the electron correlation. Results show that electron correlation has a considerable influence on the energetics and structures. Analysis of the intramolecular bond rearrangement processes reveals that, in both cases, H (or Li+) migrates in an almost elliptic path in the plane of the molecule. In HCN ↔ HNC, the migrating hydrogen interacts with the in-plane π,π* orbitals of CN, leading to a decrease in the C—N bond order. In LiCN ↔ LiNC, Li+ does not interact with the corresponding π,π* orbitals of CN. Key words: potential energy surfaces, intra-molecular bond rearrangement, bond orders, elliptic path, migration of Li+.

Theoretical Investigation of the Decarbonylation of Acetaldehyde by Ni+2 Using Density Functional Theory

2013 ◽  
Vol 446-447 ◽  
pp. 168-171
Author(s):  
Hong Fei Liu ◽  
Xin Min Min ◽  
Hai Xia Yang
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Transition Metal Ions ◽  
Basis Sets ◽  
Functional Theory ◽  
Representative System ◽  
Energy Surfaces ◽  
Ground Potential

The decarbonylation of acetaldehyde assisted by Ni+2, which was selected as a representative system of transition metal ions assisted decarbonylation of acetaldehyde, has been investigated using density functional theory (B3LYP) in conjunction with the 6-31+G** basis sets in C,H,O atoms and Lanl2dz basis sets in Ni atom The geometries and energies of the reactants, intermediates, products and transition states relevant to the reaction were located on the triplet ground potential energy surfaces of [Ni, O, C2,H4]+2. Our calculations indicate the decarbonylation of acetaldehyde takes place through four steps, that is, encounter complexation, CC activation, aldehyde H-shift and nonreactive dissociation, it is that CC activation by Ni+2that lead to the decarbonylation of acetaldehyde.

scholarly journals Multireference Electron Correlation Methods: Journeys along Potential Energy Surfaces

2020 ◽  
Vol 120 (13) ◽  
pp. 5878-5909 ◽  
Author(s):  
Jae Woo Park ◽  
Rachael Al-Saadon ◽  
Matthew K. MacLeod ◽  
Toru Shiozaki ◽  
Bess Vlaisavljevich
Keyword(s):  
Potential Energy ◽  
Electron Correlation ◽  
Potential Energy Surfaces ◽  
Correlation Methods ◽  
Energy Surfaces

DFT Study of the Spin-Forbidden Reaction of N2O with CO Catalysed by Y+ Ions

2017 ◽  
Vol 42 (1) ◽  
pp. 1-7
Author(s):  
Yongchun Tong ◽  
Qingyun Wang ◽  
Xinjian Xu ◽  
Yongcheng Wang
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Basis Sets ◽  
Intrinsic Reaction Coordinate ◽  
Effective Core Potential ◽  
Triplet Energy ◽  
Core Potential ◽  
Metal Atoms ◽  
Cyclic Reaction ◽  
Energy Surfaces

The mechanism of the cyclic reaction N2O(X1Σ+) + CO(1Σ+) → N2(X1Σg+) + CO2(1Σg+) catalysed by Y+ ions has been investigated on both singlet and triplet potential energy surfaces. The reactions were investigated by means of the relativistic effective core potential together with the Stuttgart basis sets on Y and the UB3LYP/6-311G** level of theory on non-metal atoms. The crossings involved between the singlet and triplet energy surfaces have been investigated by means of the intrinsic reaction coordinate approach used by Yoshizawa et al. Furthermore, both steps of the reaction are exothermic and the overall reaction is exothermic by 361.12 kJ mol−1.

scholarly journals Extrapolating Potential Energy Surfaces by Scaling Electron Correlation: Isomerization of Bicyclobutane to Butadiene

2008 ◽  
Author(s):  
Jesse J. Lutz ◽  
Piotr Piecuch ◽  
Pawel Danielewicz ◽  
Piotr Piecuch ◽  
Vladimir Zelevinsky
Keyword(s):  
Potential Energy ◽  
Electron Correlation ◽  
Potential Energy Surfaces ◽  
Energy Surfaces

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.

scholarly journals Torsional Potential Energy Surfaces of Dinitrobenzene Isomers

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Paul M. Smith ◽  
Mario F. Borunda
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Three Dimensional ◽  
Molecular Structures ◽  
Basis Sets ◽  
Valuable Insight ◽  
Complex Molecules ◽  
Torsional Potential ◽  
Energy Surfaces

The torsional potential energy surfaces of 1,2-dinitrobenzene, 1,3-dinitrobenzene, and 1,4-dinitrobenzene were calculated using the B3LYP functional with 6-31G(d) basis sets. Three-dimensional energy surfaces were created, allowing each of the two C-N bonds to rotate through 64 positions. Dinitrobenzene was chosen for the study because each of the three different isomers has widely varying steric hindrances and bond hybridization, which affect the energy of each conformation of the isomers as the nitro functional groups rotate. The accuracy of the method is determined by comparison with previous theoretical and experimental results. The surfaces provide valuable insight into the mechanics of conjugated molecules. The computation of potential energy surfaces has powerful application in modeling molecular structures, making the determination of the lowest energy conformations of complex molecules far more computationally accessible.

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