Molecular orbital studies of carbyne reactions: addition and insertion reaction paths for the reaction

1985 ◽  
Vol 63 (7) ◽  
pp. 1689-1693 ◽  
Author(s):  
Ratnakar K. Gosavi ◽  
Imre Safarik ◽  
Otto P. Strausz
Keyword(s):  
Activation Energy ◽  
Potential Energy ◽  
Molecular Orbital ◽  
Geometry Optimization ◽  
Open Shell ◽  
Basis Set ◽  
Insertion Reaction ◽  
Orbital Theory ◽  
Asymmetric Reaction ◽  
Geometry Analysis

Potential energy hypersurfaces have been studied for the [Formula: see text] addition and insertion reactions by abinitio molecular orbital theory. 6-31G basis set was used for complete geometry optimization of CH, C2H4, the cyclopropyl and allyl radicals as well as the reaction intermediates involved, with the RHF open shell SCF method. CI calculations were then performed at the SCF level optimized geometry. Analysis of the potential energy hypersurfaces predicts, in agreement with reported experimental data, a zero activation energy for the addition reaction via a non least motion, asymmetric reaction path, while the insertion reaction features a computed activation energy of 15 kcal mol−1.

scholarly journals LOCALLY PROJECTED MOLECULAR ORBITAL THEORY FOR MOLECULAR INTERACTION WITH A HIGH-SPIN OPEN-SHELL MOLECULE

2006 ◽  
Vol 05 (04) ◽  
pp. 819-833 ◽  
Author(s):  
SUEHIRO IWATA
Keyword(s):  
Molecular Orbital ◽  
High Spin ◽  
Closed Shell ◽  
Open Shell ◽  
Coefficient Matrix ◽  
Molecular Orbitals ◽  
Orbital Method ◽  
Stationary Condition ◽  
Orbital Theory ◽  
Stationary Conditions

Locally projected molecular orbital method for molecular interactions is extended to a cluster consisting of a high-spin open-shell molecule and many closed-shell molecules. While deriving the equations, the Hartee–Fock–Roothaan equation without the orthonormal condition is obtained. The stationary conditions for molecular orbitals are expressed in a form of a generalized Brillouin condition. To obtain the molecular orbital coefficient matrix, which satisfies the stationary condition, a single Fock operator form is presented. For the locally projected molecular orbitals for the open-shell cluster, the working matrix representaion is given.

Structures of simple anions from ab initio molecular orbital calculations

1976 ◽  
Vol 29 (8) ◽  
pp. 1635 ◽  
Author(s):  
L Radom
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Basis Set ◽  
Basis Sets ◽  
Molecular Orbital Calculations ◽  
Limited Information ◽  
Orbital Theory ◽  
Comparable Quality ◽  
Split Valence ◽  
Theoretical Results

Ab initio molecular orbital theory with the minimal STO-3G and split-valence 4-31G basis sets is used to obtain geometries of 18 anions:OH-, NH2-, HF2-, BH4-, BF4-, C22-, CN-, NCN2-, N3-, NO2-, NO3-, 0CCO2-, CO32-, HCOO-, CH3COO-, C2O42-, C4O42- and C(CN)3-. The theoretical results are compared with experimental results from the literature. The STO-3G basis set performs somewhat worse for anions than for neutral molecules. On the other hand, the 4-31G basis set gives good results and predicts bond lengths to within 0.02� for all the molecules considered. Limited information on bond angle predictions suggests that these are of comparable quality to those for neutral molecules. The tricyanomethanide ion is predicted to be planar.

scholarly journals Potential Energy Surface (PES) Scan of Gas-Phase L-Proline

2014 ◽  
Vol 38 ◽  
pp. 26-34
Author(s):  
Anouar el Guerdaoui ◽  
Yassine el Kahoui ◽  
Malika Bourjila ◽  
Rachida Tijar ◽  
Abderrahman el Gridani
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Surface ◽  
Conformational Stability ◽  
Geometry Optimization ◽  
Basis Set ◽  
Absolute Minimum ◽  
Pes Scan

We performed here a systematic ab initio calculations on neutral gas-phase L-proline. A total of 8 local minima were located by geometry optimization of the trial structures using density functional theory (DFT) with B3LYP three parameter hybrid potential coupled with the 6-31G)d( basis set. The absolute minimum obtained will be subject to a rigid potential energy surface (PES) scan by rotating its carboxylic group using the same method with more accurate basis set B3LYP/6-311++G(d,p), to get a deeper idea about its conformational stability. The main aim of the present work was the study of the rigidity of the L-proline structure and the puckering of its pyrrolidine ring.

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