Theoretical study on the chemical formation mechanism of a β-myrcene ozonolysis reaction under atmospheric conditions

2012 ◽  
Vol 90 (8) ◽  
pp. 708-715 ◽  
Author(s):  
Yuyang Zhao ◽  
Jing Bai ◽  
Chenxi Zhang ◽  
Chen Gong ◽  
Xiaomin Sun
Keyword(s):  
Rate Constants ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Single Point ◽  
State Theory ◽  
Tunneling Effect ◽  
Atmospheric Conditions ◽  
Functional Theory ◽  
Real Atmosphere ◽  
Energy Surfaces

Density functional theory (DFT) was used to study the β-myrcene ozonolysis reaction. The reactants, intermediates, transition states, and products were optimized at the MPWB1K/6–31G(d,p) level. The single-point energies were performed at the MPWB1K/6–311+G(3df,2p) level. The profiles of the potential energy surfaces were constructed and the rate constants of the reaction steps were analyzed. The possible reaction mechanisms for the ozonolysis intermediates in real atmosphere are also discussed. Based on quantum chemistry information, the rate constants were calculated using Rice–Ramsperger–Kassel–Marcus (RRKM) theory and the canonical variational transition-state theory (CVT) with small curvature tunneling effect (SCT). Arrhenius equations of rate constants over the temperature range of 200–800 K are provided, and the lifetimes of the reaction species in the troposphere were estimated according to rate constants.

scholarly journals The ANI-1ccx and ANI-1x Data Sets, Coupled-Cluster and Density Functional Theory Properties for Molecules

2020 ◽  
Author(s):  
Justin S. Smith ◽  
Roman Zubatyuk ◽  
Benjamin T. Nebgen ◽  
Nicholas Lubbers ◽  
Kipton Barros ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Atomic Charge ◽  
Density Functional Theory Calculations ◽  
Coupled Cluster ◽  
Data Sets ◽  
Data Set ◽  
Functional Theory ◽  
Energy Surfaces

<p>Maximum diversification of data is a central theme in building generalized and accurate machine learning (ML) models. In chemistry, ML has been used to develop models for predicting molecular properties, for example quantum mechanics (QM) calculated potential energy surfaces and atomic charge models. The ANI-1x and ANI-1ccx ML-based eneral-purpose potentials for organic molecules were developed through active learning; an automated data diversification process. Here, we describe the ANI-1x and ANI-1ccx data sets. To demonstrate data set diversity, we visualize them with a dimensionality reduction scheme, and contrast against existing data sets. The ANI-1x data set contains multiple QM properties from 5M density functional theory calculations, while the ANI-1ccx data set contains 500k data points obtained with an accurate CCSD(T)/CBS extrapolation. Approximately 14 million CPU core-hours were expended to generate this data. Multiple QM properties from density functional theory and coupled cluster are provided: energies, atomic forces, multipole moments, atomic charges, and more. We provide this data to the community to aid research and development of ML models for chemistry.</p>

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 Acid Dissociation in (HX)n(H2O)n Clusters (X = F, Cl, Br, I; N = 2, 3)

2019 ◽  
Author(s):  
Alba Vargas-Caamal ◽  
Eugenia Dzib ◽  
Filiberto Ortiz-Chi ◽  
Albeiro Restrepo ◽  
Gabriel Merino
Keyword(s):  
Potential Energy Surfaces ◽  
Density Functional ◽  
Global Minimum ◽  
Acid Dissociation ◽  
Water Molecules ◽  
Functional Theory ◽  
Cooperative Effects ◽  
Systematic Exploration ◽  
Density Functional Theory Computations ◽  
Energy Surfaces

The interactions between two or three hydrogen halide molecules and the same number of water moieties are investigated through a systematic exploration of the corresponding potential energy surfaces using a stochastic methodology in conjunction with density functional theory computations. Our results indicate that HF, the weakest acid in the series, is partially dissociated. Similarly, HCl, HBr, and HI undergo dissociation in the presence of three, two, and two water molecules, respectively. The decrease in the number of water molecules required for dissociation, when compared with clusters with one single HX molecule, suggests cooperative effects. Interestingly, the hydrogen-bridged bihalide anions (XHX<sup>-</sup>) are present in the global minimum of (HX)n(H2O)n<sub> </sub> clusters with X = Br, I and n = 2, 3.<br>

scholarly journals Multireference Ground and Excited State Electronic Structures of Free- versus Iron Porphyrin-Carbenes

2019 ◽  
Author(s):  
Gautam Stroscio ◽  
Martin Srnec ◽  
Ryan Hadt
Keyword(s):  
Excited State ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Closed Shell ◽  
Axial Ligand ◽  
Iron Porphyrin ◽  
Functional Theory ◽  
Reaction Coordinates ◽  
Ligand Charge Transfer ◽  
Energy Surfaces

Iron porphyrin carbenes (IPCs) are important reaction intermediates in engineered carbene transferase enzymes and homogeneous catalysis. However, discrepancies between theory and experiment complicate the understanding of IPC electronic structure (i.e., open- vs. closed-shell singlet (OSS vs. CSS)). Here we investigate the structurally dependent ground and excited spin state energetics of a free carbene and its IPC analogs. Only multireference <i>ab initio</i> wave function methods are consistent with experiment and predict a CSS ground state (Fe(II)←{:C(X)Y}<sup>0</sup>), contrary to density functional theory (DFT). The OSS is a high-lying metal-to-ligand charge transfer (MLCT) excited state that is sensitive to the nature of the axial ligand. Furthermore, potential energy surfaces (PESs) along the Fe–C bond elongation coordinate exhibit strong mixings between CSS/OSS characters, which can be an important feature for describing reaction mechanisms. Future studies on IPC reaction coordinates should evaluate contributions from ground and excited state multireference character. <br>

scholarly journals Addition Coupled Electron Transfer (ACET) and Addition Coupled Electron Coupled Proton Transfer (ACPCET)

2021 ◽  
Author(s):  
Yumiao Ma
Keyword(s):  
Electron Transfer ◽  
Proton Transfer ◽  
Nucleophilic Addition ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Classical Trajectory ◽  
Functional Theory ◽  
Energy Surfaces ◽  
Theory Calculation

The new types of elementary reaction in which a nucleophilic addition (A) to quinones is coupled with electron transfer (ET) and even further proton transfer (PT) are suggested herein by density functional theory calculation, which are called Addition Coupled Electron Transfer (ACET) or Addition Coupled Electron Coupled Proton Transfer (ACPCET). With a [2.2]paracyclophane-derived biquinone (1) as the substrate, the nature of nucleophilic addition onto its sp2 carbons exhibits a change from stepwise A-ET-PT to ACET-PT and further to ACPCET, in parallel with the decreased nucleophilicity of the attacking reagent. In addition, we further proposed six possible potential energy surfaces and the coupling modes between A, ET and PT, in which three have been found in this work. Quasi-classical trajectory shows that the ACET and PT event can also be dynamically concerted even for an ACET-PT mechanism.

Kinetics and mechanism for chlorine-initiated atmospheric oxidation of ethyl formate

2014 ◽  
Vol 92 (7) ◽  
pp. 598-604 ◽  
Author(s):  
Yan Zhao ◽  
Xiaomin Sun ◽  
Wenxing Wang ◽  
Laixiang Xu
Keyword(s):  
Rate Constants ◽  
Density Functional ◽  
Single Point ◽  
Oxidation Mechanism ◽  
Density Functional Theory Method ◽  
Ethyl Formate ◽  
Stationary Points ◽  
Atmospheric Conditions ◽  
Point Energy ◽  
Rearrangement Reaction

The chlorine-initiated reaction mechanism of ethyl formate in the atmosphere was investigated using the density functional theory method. The geometry parameters and frequencies of all of the stationary points were calculated at the B3LYP/ 6-31G(d,p) level. The single-point energy calculations were carried out at different levels, including MP2/6-31G(d), MP2/6-311++G(d,p), and CCSD(T)/6-31G(d). A detailed oxidation mechanism is provided and discussed. Present results show that α-ester rearrangement reaction and the O2 direct abstraction from IM6 (HC(O)OCH(O)CH3) are the more favorable pathway and are competitive. The 1,4-H shift isomerization of IM6 proved to be feasible under general atmospheric conditions. The decomposition of IM18 (CH3CH2OC(O)O) is favorable both thermodynamically and kinetically. Canonical variational transition theory with small-curvature tunneling correction was employed to predict the rate constants. The overall rate constant of ethyl formate at 298 K is 8.63 × 10−12 cm3 molecule−1 s−1. The Arrhenius equations of rate constants at the temperature range of 200–380 K were fitted.

Sign in / Sign up

Export Citation Format

Share Document