Atomic-scale studies of chemical and transport processes relevant to propellant combustion

2018 ◽  
Author(s):  
◽  
Rezvan Chitsazi
Keyword(s):  
Ground State ◽  
Density Functional ◽  
Minimum Energy ◽  
Transport Processes ◽  
Electronic Ground State ◽  
Atomic Scale ◽  
Stationary Points ◽  
Insertion Reaction ◽  
Electronic Ground ◽  
Minimum Energy Pathway

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Density functional theory (DFT) and correlated molecular orbital electronic structure calculations were used to study the Al + CO2 [subscript arrow] AlO + CO reaction on the electronic ground-state potential-energy surface (PES). Geometries were optimized using DFT (M11/jun-cc-pV(Q+d)Z) and more accurate energies were obtained using the composite Weizmann-1 theory with Brueckner doubles (W1BD). The results comprise the most complete, most systematic characterization of the Al + CO2 reaction surface to date and are based on consistent application of high-level methods for all stationary points identified. The pathways from Al + CO[subscript 2] to AlO + CO on the electronic ground-state PES all involve formation of one or more stable AlCO2 complexes denoted ?-AlCO2, trans-AlCO[subscript 2], and C[subscript 2v]-AlCO[subscript 2], among which [subscript n]-AlCO[subscript 2] and C[subscript 2v]-AlCO[subscript 2] are the least and most stable, respectively. We report a new minimum-energy pathway for the overall reaction, namely formation of [subscript n]-AlCO[subscript 2] from reactants and dissociation of that same complex to products via a bond-insertion reaction that passes through a fourth (weakly metastable) AlCO[subscript 2] complex denoted cis-OAlCO. Natural Bond Orbital analysis was applied to study trends in charge distribution and the degree of charge transfer in key structures along the minimum-energy pathway. The process of aluminum insertion into CO[subscript 2] is discussed in the context of analogous processes for boron and first-row transition metals. ...

The Nearly Degenerate Triplet Electronic Ground State Isomers of Lithium Nitroxide

2007 ◽  
Vol 72 (2) ◽  
pp. 129-152 ◽  
Author(s):  
Justin M. Turney ◽  
Henry F. Schaefer
Keyword(s):  
Ground State ◽  
Global Minimum ◽  
Electronic Ground State ◽  
Basis Sets ◽  
Stationary Points ◽  
Mechanical Methods ◽  
State Potential ◽  
Correlation Consistent ◽  
Highly Correlated ◽  
Electronic Ground

The triplet electronic ground state potential energy surface of lithium nitroxide has been systematically investigated using convergent quantum mechanical methods. Equilibrium structures and physical properties for five stationary points (three minima and two transition states) have been determined employing highly correlated coupled cluster theory with four correlation-consistent polarized-valence (cc-pVXZ and aug-cc-pVXZ, X = T and Q) and two core correlation-consistent polarized-valence (cc-pCVXZ, X = T and Q) basis sets. The global minimum, roughly L-shaped Li-O-N, is predicted to lie 6.5 kcal mol-1 below the linear LiON minimum and 2.4 kcal mol-1 below the linear LiON minimum. The barrier to isomerization from the global minimum to LiON was found to be 7.4 kcal mol-1 and with regard to LiNO 6.9 kcal mol-1. The dissociation energies, D0, with respect to Li + NO, have been predicted for all minima and for the global minimum was found to be 34.9 kcal mol-1.

scholarly journals DENSITY FUNCTIONAL ELECTRONIC SPECTRUM OF THE CuO6-10 CLUSTER AND POSSIBLE LOCAL JAHN–TELLER DISTORTIONS IN THE La–Ba–Cu–O SUPERCONDUCTOR

2004 ◽  
Vol 18 (13) ◽  
pp. 1937-1949
Author(s):  
J. R. SOTO ◽  
J. J. CASTRO ◽  
E. YÉPEZ ◽  
A. CALLES
Keyword(s):  
Ground State ◽  
Density Functional ◽  
Dft Calculation ◽  
A Priori ◽  
Electronic Ground State ◽  
Necessary Condition ◽  
Generalized Gradient ◽  
Local Distortion ◽  
Jahn Teller ◽  
Electronic Ground

We present a density functional theory (DFT) calculation in the generalized gradient approximation to study the possibility for the existence of Jahn–Teller (JT) or pseudo Jahn–Teller (PJT) type local distortions in the La – Ba – Cu – O superconducting system. We performed the calculation and correspondingly group theory classification of the electronic ground state of the CuO 6-10 elongated octahedra cluster, immersed in a background simulating the superconductor. Part of the motivation to do this study is that the origin of the apical deformation of the CuO 6-10 cluster is not due to a pure JT effect, having therefore a non a priori condition to remove the degeneracy of the electronic ground state of the parent regular octahedron. We present a comparative analysis of the symmetry classified electron spectrum with previously reported results using unrestricted Hartree–Fock calculations (UHF). Both the DFT and UHF calculations produced a non-degenerate electronic ground state, not having therefore the necessary condition for a pure JT effect. However, the appearance of a degenerate E g state near to the highest occupied molecular orbital in the DFT calculation, suggests the possibility for a PJT effect responsible for a local distortion of the oxidized [Formula: see text] cluster.

scholarly journals Bonding in M(NHBMe)2 and M[Mn(CO)5]2 complexes (M=Zn, Cd, Hg; NHBMe=(HCNMe)2B): divalent group 12 metals with zero oxidation state

2021 ◽  
Vol 140 (6) ◽  
Author(s):  
Sudip Pan ◽  
Lili Zhao ◽  
Gernot Frenking
Keyword(s):  
Oxidation State ◽  
Ground State ◽  
Density Functional ◽  
Electronic Ground State ◽  
Electron Configuration ◽  
Acceptor Interaction ◽  
Bond Dissociation ◽  
Group 12 ◽  
Group 12 Metals ◽  
Electronic Ground

AbstractQuantum chemical studies using density functional theory were carried out on M(NHBMe)2 and M[Mn(CO)5]2 (M=Zn, Cd, Hg) complexes. The calculations suggest that M(NHBMe)2 and M[Mn(CO)5]2 have D2d and D4d symmetry, respectively, with a 1A1 electronic ground state. The bond dissociation energies of the ligands have the order of Zn > Cd > Hg. A thorough bonding analysis using charge and energy decomposition methods suggests that the title complexes are best represented as NHBMe⇆M0⇄NHBMe and Mn(CO)5⇆M0⇄Mn(CO)5 where the metal atom M in the electronic ground state with an ns2 electron configuration is bonded to the (NHBMe)2 and [Mn(CO)5]2 ligands through donor–acceptor interaction. These experimentally known complexes are the first examples of mononuclear complexes with divalent group 12 metals with zero oxidation state that are stable at ambient condition. These complexes represent the rare situation where the ligands act as a strong acceptor and the metal center acts as strong donor. The relativistic effect of Hg leads to a weaker electron donating strength of the 6s orbital, which explains the trend of the bond dissociation energy.

Theoretical Study on the Mechanism of Reaction of Ground-State Fe Atoms with Carbon Dioxide

2004 ◽  
Vol 69 (1) ◽  
pp. 13-33 ◽  
Author(s):  
Dimitrios A. Pantazis ◽  
Athanassios C. Tsipis ◽  
Constantinos A. Tsipis
Keyword(s):  
Ground State ◽  
Density Functional ◽  
Activation Barrier ◽  
Spectroscopic Properties ◽  
Basis Sets ◽  
Stationary Points ◽  
Insertion Reaction ◽  
Weakly Bound ◽  
Satisfactory Description ◽  
Bonding Properties

Density functional calculations at the B3LYP level of theory, using the 6-31G(d) and 6-311+G(3df) basis sets, provide a satisfactory description of the geometric and energetic reaction profile of the Fe + CO2 → FeO + CO reaction. The reaction is predicted to be endothermic by 23.24 kcal/mol at the B3LYP/6-311+G(3df)//B3LYP/6-31G(d) level of theory and to proceed by formation of either a Fe(η2-OCO) or a Fe(η3-OCO) intermediate. The Fe(η2-OCO) intermediate in the 5A' ground state is weakly bound with respect to Fe(5D) and CO2 dissociation products by 0.78 (2.88) kcal/mol at the B3LYP/6-31G(d) (B3LYP/6-311+ G(3df)//B3LYP/6-31G(d)) levels of theory. In contrast, the Fe(η3-OCO) intermediate in the 5A1 ground state is unbound with respect to Fe(5D) and CO2 dissociation products by 8.27 (11.15) kcal/mol at the same levels of theory. However, both intermediates are strongly bound relative to the separated Fe+(6D) and [CO2]- anion; the computed bond dissociation energies for the Fe(η2-OCO) and Fe(η3-OCO) intermediates are 207.33 and 198.28 kcal/mol in terms of ∆E0 at the B3LYP/6-31G(d), respectively. In the Fe(η2-OCO) and Fe(η3-OCO) intermediates, an intramolecular insertion reaction of the Fe atom to O-C bond takes place yielding the isomeric OFe(η1-CO) and OFe(η1-OC) products, respectively, with a relatively low activation barrier of 25.24 (21.69) and 26.36 (23.38) kcal/mol at the B3LYP/6-31G(d) (B3LYP/6-311+G(3df)//B3LYP/6-31G(d)) levels of theory, respectively. The calculated structures, relative stability and bonding properties of all stationary points are discussed with respect to computed electronic and spectroscopic properties, such as charge density distribution and harmonic vibrational frequencies.

ChemInform Abstract: TRIPLET ELECTRONIC GROUND STATE OF TRIMETHYLENEMETHANE

1974 ◽  
Vol 5 (33) ◽  
pp. no-no
Author(s):  
DAVID R. YARKONY ◽  
HENRY F. III SCHAEFER
Keyword(s):  
Ground State ◽  
Electronic Ground State ◽  
Electronic Ground

Consistent characterization of the electronic ground state of Iron (II) Phthalocyanine from valence and core-shell electron spectroscopy

2021 ◽  
Author(s):  
Jonathan Laurent ◽  
John Bozek ◽  
Marc BRIANT ◽  
Pierre Carcabal ◽  
Denis Cubaynes ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Electron Spectroscopy ◽  
Organometallic Compound ◽  
Electronic Ground State ◽  
Core Shell ◽  
Shell Electron ◽  
Phthalocyanine Molecule ◽  
Electronic Ground

We studied the Iron (II) Phthalocyanine molecule in the gas-phase. It is a complex transition organometallic compound, for which, the characterization of its electronic ground state is still debated more...

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