scholarly journals Numerical methods in understanding reaction pathways NOx oxidation

2016 ◽  
Vol 15 (3) ◽  
pp. 075-081
Author(s):  
Justyna Jaroszyńska-Wolińska ◽  
Szymon Malinowski
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Atmospheric Pressure Plasma ◽  
Basis Sets ◽  
Chemical Models ◽  
Energetic Analysis ◽  
Energy Surfaces ◽  
Oxidation Of No ◽  
Fine Potential ◽  
Reaction Chain

Different quantum chemical models were applied in energetic analysis of process of oxidation of NO and NO2 through reaction with ozone generated by non-thermal equilibrium (low temperature), atmospheric pressure plasma. The potential energy surfaces of systems comprising NO and NO2 with ozone were characterized. The NOx oxidation processes well known, at the molecular level, were modelled by ab initio quantum methods to calculate the total reaction energy, Et, of each step in the reaction chain. Chemistry was further applied in an attempt to detect the presence of any transition states to calculate the activation energy, Ea, of reactions (1) NO + O3 and (2) NO2 + O3 using the MP2 level of theory with three different basis sets and fine potential energy scan resolution.

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.

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+.

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.

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.

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.

THEORETICAL STUDY ON HBeP- AND HPBe- ANIONS USING MULTICONFIGURATION SECOND-ORDER PERTURBATION THEORY

2012 ◽  
Vol 11 (06) ◽  
pp. 1281-1288
Author(s):  
WEN-ZUO LI ◽  
YU-WEI PEI ◽  
CAI-XIA SUN ◽  
QING-ZHONG LI ◽  
JIAN-BO CHENG
Keyword(s):  
Potential Energy ◽  
Ground State ◽  
Potential Energy Surfaces ◽  
Saddle Points ◽  
Basis Sets ◽  
Stationary Points ◽  
Electron Systems ◽  
Energy Surfaces ◽  
First Time ◽  
Atomic Natural Orbital

Some low-lying states of the nine-valence-electron systems HBeP - and HPBe - anions have been studied for the first time using three methods CASSCF, CASPT2 and B3LYP with the contracted atomic natural orbital (ANO) and cc-pVTZ basis sets. The geometries of all stationary points along the potential energy surfaces were optimized at the CASSCF/ANO, CASPT2/ANO and B3LYP/cc-pVTZ levels. The potential energy curves of isomerization reactions between HBeP - and HPBe - were calculated as a function of HBeP bond angle. The ground and the first excited states of HBeP - are predicted to be X2Π and A2Σ+ states, respectively. The X2Σ+ and A2Π states of the linear HPBe - are both first-order saddle points because they have unique imaginary frequency. Two bent minima M1 and M2 were found along the 12A′ and 12A″ potential energy surfaces, respectively. The calculated results indicated that the ground-state HBeP - is linear, while the ground-state HPBe - is bent.

Synthesis, Characterization and TheoreticalStudies of Nand#39;-(4-methoxybenzylidene)benzenesulfonohydrazide

2021 ◽  
Vol 43 (2) ◽  
pp. 212-212
Author(s):  
H G zin Aslan and L tfiye Aydin H G zin Aslan and L tfiye Aydin
Keyword(s):  
Potential Energy ◽  
Gas Phase ◽  
Vibrational Spectra ◽  
Potential Energy Surfaces ◽  
Solid Phase ◽  
Nbo Analysis ◽  
Basis Set ◽  
Basis Sets ◽  
Stable Conformer ◽  
Energy Surfaces

Nand#39;-(4-methoxybenzylidene)benzenesulfonohydrazide was synthesized and elemental analysis was conducted; IR, Raman, 1H, and 13C NMR spectral data were recorded. The potential energy surfaces (PES) of the Nand#39;-(4-methoxybenzylidene)benzenesulfonohydrazide molecule were obtained by selected degree of torsional freedom, which varied from 0o to 360and#186; in 4and#186; increments. The conformers were optimized by using a (DFT/B3LYP/6-31G(d,p)) basis set in the gas phase. The eleven conformers in the gas phase of the obtained molecule were determined and the most stable conformer (conformer 1) was re-optimized by three different basis sets of 6-31G(d,p), 6-311G(d,p), and LanL2Dz. HOMO-LUMO analyses were performed. NBO analysis was performed to describe the around of intramolecular charge transfer. The vibrational spectra were measured in solid phase IR and detailed analysis of the vibrational spectra of conformer 1 was done; all the bands of the spectra were interpreted by the use of the potential energy distributions (PED) and the molecular electrostatic potential (MEP) was plotted.

THEORETICAL STUDY ON THE H2 ACTIVATION BY PtO+ AND ${\rm PtO}_{2}^{+}$ IN THE GAS PHASE

2010 ◽  
Vol 09 (06) ◽  
pp. 963-974 ◽  
Author(s):  
YONGCHUN TONG ◽  
QINGYUN WANG ◽  
DONGQING WU ◽  
YONGCHENG WANG
Keyword(s):  
Potential Energy ◽  
Gas Phase ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Reaction Pathway ◽  
Minimum Energy ◽  
Basis Sets ◽  
Avoided Crossing ◽  
Pass Through ◽  
Energy Surfaces

Gas-phase H2 activation by PtO+ and [Formula: see text] were studied at the density functional level of theory (DFT) using the relativistic effective core potential (RECP) of Stuttgart basis sets on platinum atom and UB3LYP/6-311+G(2d,2p) level on hydrogen and oxygen atoms. Two reaction profiles corresponding to the doublet and quartet multiplicities were investigated in order to ascertain the presence of some spin inversion during the H2 reduction. The electron-transfer reactivity of the reactions were analyzed using the two-state model, and the strongly crossing behavior on the transition state (TS) area were shown. Finally, the actions of frontier molecular orbitals in minimum-energy crossing point (MECP) have been illuminated briefly. These theoretical results can act as a guide to further theoretical and experimental research. H2 activation mediated by metal oxide cations were found to be an exothermic spin-forbidden process resulting from a crossing between quartet and doublet profiles. To evaluate the spin-forbidden process in the reaction pathway, the spin-obit coupling (SOC) matrix elements are calculated at the MECP with the different potential energy surfaces (PESs) and the probability of crossing between the adiabatic potential-energy surfaces during a single pass through the avoided crossing region was described. Therefore, the intersystem crossing (ISC) at crossing points (CP) occur efficiently because of the large SOC (ca. 85.58 cm-1) involved.

Sign in / Sign up

Export Citation Format

Share Document