The Experts below are selected from a list of 9555 Experts worldwide ranked by ideXlab platform
Joseph W. Bozzelli - One of the best experts on this subject based on the ideXlab platform.
-
Thermochemical Properties: Enthalpy, Entropy, and Heat Capacity of C2-C3 Fluorinated Aldehydes. Radicals and Fluorocarbon Group Additivity.
The journal of physical chemistry. A, 2019Co-Authors: Douglas L. Purnell, Joseph W. BozzelliAbstract:Thermochemical Properties of fluorinated aldehydes are important for understanding their stability and reactions in the environment and in thermal processes. Structures and Thermochemical Properties of C1 to C3 fluorinated aldehydes are determined by use of computational chemistry. Standard enthalpies of formation for 30 C2- and C3-fluorinated aldehydes and 31 radicals were calculated with 11 different ab initio and density functional theory methods: CBS-APNO, CBS-4M, CBS-QB3, M06-2X, ωB97X, B3LYP, G-2, G-3, G-4, and W1U via several series of isodesmic reactions. Entropy, S°298, and heat capacities, Cp(T)’s (300 ≤ T/K ≤ 1500) from vibration, translation, and external rotation contributions are calculated on the basis of the vibration frequencies and structures obtained from the B3LYP/6-31++G(d,p) density functional method. Potential barriers for the internal rotations are also from this method and used to calculate hindered rotor contributions to S°298 and Cp(T)’s using direct integration over energy leve...
-
Thermochemical Properties and Bond Dissociation Energies for Fluorinated Methanol, CH3-xFxOH, and Fluorinated Methyl Hydroperoxides, CH3-xFxOOH: Group Additivity
The journal of physical chemistry. A, 2016Co-Authors: Heng Wang, Joseph W. BozzelliAbstract:Oxygenated fluorocarbons are routinely found in sampling of environmental soils and waters as a result of the widespread use of fluoro and chlorofluoro carbons as heat transfer fluids, inert materials, polymers, fire retardants and solvents; the influence of these chemicals on the environment is a growing concern. The Thermochemical Properties of these species are needed for understanding their stability and reactions in the environment and in thermal process. Structures and Thermochemical Properties on the mono- to trifluoromethanol, CH3–xFxOH, and fluoromethyl hydroperoxide, CH3–xFxOOH (1 ≤ x ≤ 3), are determined by CBS-QB3, CBS-APNO, and G4 calculations. Entropy, S°298, and heat capacities, Cp(T)’s (300 ≤ T/K ≤ 1500) from vibration, translation, and external rotation contributions are calculated on the basis of the vibration frequencies and structures obtained from the B3LYP/6-31+G(d,p) density functional method. Potential barriers for the internal rotations are also calculated from this method and use...
-
Thermochemical Properties for Isooctane and Carbon Radicals: Computational Study
The journal of physical chemistry. A, 2013Co-Authors: Suarwee Snitsiriwat, Joseph W. BozzelliAbstract:Thermochemical Properties for isooctane, its internal rotation conformers, and radicals with corresponding bond energies are determined by use of computational chemistry. Enthalpies of formation are determined using isodesmic reactions with B3LYP density function theory and composite CBS-QB3 methods. Application of group additivity with comparison to calculated values is illustrated. Entropy and heat capacities are determined using geometric parameters, internal rotor potentials, and frequencies from B3LYP/6-31G(d,p) calculations for the lowest energy conformer. Internal rotor potentials are determined for the isooctane parent and for the primary, secondary, and tertiary radicals in order to identify isomer energies. Intramolecular interactions are shown to have a significant effect on the enthalpy of formation of the isooctane parent and its radicals. The computed standard enthalpy of formation for the lowest energy conformers of isooctane from this study is −54.40 ± 1.60 kcal mol–1, which is 0.8 kcal mo...
-
Thermochemical Properties and Bond Dissociation Energies of C3–C5 Cycloalkyl Hydroperoxides and Peroxy Radicals: Cycloalkyl Radical + 3O2 Reaction Thermochemistry
The journal of physical chemistry. A, 2012Co-Authors: Itsaso Auzmendi-murua, Joseph W. BozzelliAbstract:Cyclic aliphatic hydrocarbons are major components in modern fuels; they can be present in the reactants, and they can be formed during the gas-phase oxidation processes. In combustion and thermal oxidation processes, these cyclics will form radicals that react with 3O2 to form peroxy radicals. In this study, density functional theory and higher level ab initio calculations are used to calculate Thermochemical Properties and bond dissociation energies of 3–5-membered cycloalkanes, corresponding hydroperoxides, hydroperoxycycloalkyl radicals, and cycloalkyl radicals that occur in these reaction systems. Geometries, vibration frequencies, and Thermochemical Properties, ΔHf 298°, are calculated with the B3LYP/6-31 g(d,p), B3LYP/6-31 g(2d,2p), composite CBS-QB3, and G3MP2B3 methods. Standard enthalpies of formation at 298 K are evaluated using isodesmic reaction schemes with several work reactions for each species. Group additivity contributions are developed, and application of group additivity with comparis...
-
Structure and Thermochemical Properties of 2-Methoxyfuran, 3-Methoxyfuran, and Their Carbon-Centered Radicals Using Computational Chemistry
The journal of physical chemistry. A, 2010Co-Authors: Jason M. Hudzik, Joseph W. BozzelliAbstract:Methoxyfurans are known components in a number of biofuel synthesis processes and their Thermochemical Properties are important to the stability, reaction paths, and chemical kinetics of these spec...
Guillaume Van Der Rest - One of the best experts on this subject based on the ideXlab platform.
-
Thermochemical Properties of the ammonia-water ionized dimer probed by ion-molecule reactions.
Journal of Physical Chemistry A, 2005Co-Authors: Safwat Azeim, Guillaume Van Der RestAbstract:The Thermochemical Properties of some small clusters such as the (H2O)2*+ dimer have already been investigated by both experimental and theoretical methods. The recent method to selectively prepare the ammonia-water ionized dimer [NH3, H2O]*+ (and not its proton transfer isomer [NH4+, OH*]) allowed us to study its chemical reactivity. This study focuses on the charge and proton transfer pathways: Ion-molecule reactions in the cell of an FT-ICR mass spectrometer were carried out with a range of organic compounds. Examination of the reactivity of the [NH3, H2O]*+ ionized dimer versus ionization energy and proton affinity of the neutral reagents shows a threshold in the reactivity in both instances. This leads to a bracketing of Thermochemical Properties related to the dimer. From these experiments and in agreement with ab initio calculations, the adiabatic recombination energy of the [NH3, H2O]*+ dimer was evaluated at -9.38 +/- 0.04 eV. The proton affinity bracketing required the reevaluation of two reference gas-phase basicity values. The results, in good agreement with the calculation, lead to an evaluation of the proton affinity of the [NH2*, H2O] dimer at 204.4 +/- 0.9 kcal mol(-1). These two experimental values are respectively related to the ionization energy of NH3*+ and to the proton affinity of NH2* by the difference in single water molecule solvation energies of ionized ammonia, of neutral ammonia, and of the NH2* radical.
-
Thermochemical Properties of the ammonia-water ionized dimer probed by ion-molecule reactions.
The journal of physical chemistry. A, 2005Co-Authors: Safwat Azeim, Guillaume Van Der RestAbstract:The Thermochemical Properties of some small clusters such as the (H2O)2•+ dimer have already been investigated by both experimental and theoretical methods. The recent method to selectively prepare the ammonia−water ionized dimer [NH3, H2O]•+ (and not its proton transfer isomer [NH4+, OH•]) allowed us to study its chemical reactivity. This study focuses on the charge and proton transfer pathways: Ion−molecule reactions in the cell of an FT-ICR mass spectrometer were carried out with a range of organic compounds. Examination of the reactivity of the [NH3, H2O]•+ ionized dimer versus ionization energy and proton affinity of the neutral reagents shows a threshold in the reactivity in both instances. This leads to a bracketing of Thermochemical Properties related to the dimer. From these experiments and in agreement with ab initio calculations, the adiabatic recombination energy of the [NH3, H2O]•+ dimer was evaluated at −9.38 ± 0.04 eV. The proton affinity bracketing required the reevaluation of two referen...
Kurt V. Mikkelsen - One of the best experts on this subject based on the ideXlab platform.
-
benchmark study of the structural and Thermochemical Properties of a dihydroazulene vinylheptafulvene photoswitch
Journal of Physical Chemistry A, 2017Co-Authors: Mads Koerstz, Jonas Elm, Kurt V. MikkelsenAbstract:We investigate the performance of four different density functional theory (DFT) functionals (M06-2X, ωB97X-D, PBE0, and B3LYP-D3BJ) for calculating the structural and Thermochemical Properties of the dihydroazulene/vinylheptafulvene photoswitch (DHA/VHF). We find that all the tested DFT functionals yield equilibrium geometries in good agreement with higher level CCSD/cc-pVDZ calculations and that the basis set had little influence on the geometries of the photoswitch. We found a negligible difference in the thermal contribution to the Gibbs free energy between the tested functionals, indicating that the largest source of error when calculating storage free energies originates from errors in the calculated single point energies. It was found that ωB97X-D and M06-2X performed decently for predicting storage energies. While B3LYP-D3BJ and PBE0 generally underestimated the storage energy compared to CCSD(T)-F12a/VDZ-F12 results. Therefore, we tested if domain based local pair natural orbital coupled-cluster ...
-
Benchmark Study of the Structural and Thermochemical Properties of a Dihydroazulene/Vinylheptafulvene Photoswitch.
The journal of physical chemistry. A, 2017Co-Authors: Mads Koerstz, Jonas Elm, Kurt V. MikkelsenAbstract:We investigate the performance of four different density functional theory (DFT) functionals (M06-2X, ωB97X-D, PBE0, and B3LYP-D3BJ) for calculating the structural and Thermochemical Properties of the dihydroazulene/vinylheptafulvene photoswitch (DHA/VHF). We find that all the tested DFT functionals yield equilibrium geometries in good agreement with higher level CCSD/cc-pVDZ calculations and that the basis set had little influence on the geometries of the photoswitch. We found a negligible difference in the thermal contribution to the Gibbs free energy between the tested functionals, indicating that the largest source of error when calculating storage free energies originates from errors in the calculated single point energies. It was found that ωB97X-D and M06-2X performed decently for predicting storage energies. While B3LYP-D3BJ and PBE0 generally underestimated the storage energy compared to CCSD(T)-F12a/VDZ-F12 results. Therefore, we tested if domain based local pair natural orbital coupled-cluster ...
-
Computational Methodology Study of the Optical and Thermochemical Properties of a Molecular Photoswitch
The journal of physical chemistry. A, 2015Co-Authors: Stine T. Olsen, Jonas Elm, Freja Eilsø Storm, Aske Nørskov Gejl, Anne S. Hansen, Mia Harring Hansen, Jens Rix Nikolajsen, Mogens Brøndsted Nielsen, Henrik G. Kjaergaard, Kurt V. MikkelsenAbstract:We assess how the utilization of different DFT functionals for obtaining the equilibrium geometries and vibrational frequencies affect the description of the thermochemistry and subsequent calculation of the optical Properties of a dihydroazulene–vinylheptafulvene photoswitch. The assessment covers nine popular DFT functionals (BLYP, B3LYP, CAM-B3LYP, M06-L, M06, M06-2X, PBE, PBE0, and ωB97X-D) in conjugation with five different Pople style basis sets (6-31+G(d), 6-31++G(d,p), 6-311+G(d), 6-311++G(d,p), and 6-311++G(3df,3pd)). It is identified that only CAM-B3LYP, M06-2X, and PBE0 are able to quantitatively describe the correct trends in the Thermochemical Properties. The subsequent calculation of the optical Properties using the CAM-B3LYP functional shows that there is little difference in whether the CAM-B3LYP, M06-2X, or PBE0 functionals have been used to calculate the equilibrium geometries. Utilizing the identified functionals, we investigate how the number of electron withdrawing cyano substituents ...
Safwat Azeim - One of the best experts on this subject based on the ideXlab platform.
-
Thermochemical Properties of the ammonia-water ionized dimer probed by ion-molecule reactions.
Journal of Physical Chemistry A, 2005Co-Authors: Safwat Azeim, Guillaume Van Der RestAbstract:The Thermochemical Properties of some small clusters such as the (H2O)2*+ dimer have already been investigated by both experimental and theoretical methods. The recent method to selectively prepare the ammonia-water ionized dimer [NH3, H2O]*+ (and not its proton transfer isomer [NH4+, OH*]) allowed us to study its chemical reactivity. This study focuses on the charge and proton transfer pathways: Ion-molecule reactions in the cell of an FT-ICR mass spectrometer were carried out with a range of organic compounds. Examination of the reactivity of the [NH3, H2O]*+ ionized dimer versus ionization energy and proton affinity of the neutral reagents shows a threshold in the reactivity in both instances. This leads to a bracketing of Thermochemical Properties related to the dimer. From these experiments and in agreement with ab initio calculations, the adiabatic recombination energy of the [NH3, H2O]*+ dimer was evaluated at -9.38 +/- 0.04 eV. The proton affinity bracketing required the reevaluation of two reference gas-phase basicity values. The results, in good agreement with the calculation, lead to an evaluation of the proton affinity of the [NH2*, H2O] dimer at 204.4 +/- 0.9 kcal mol(-1). These two experimental values are respectively related to the ionization energy of NH3*+ and to the proton affinity of NH2* by the difference in single water molecule solvation energies of ionized ammonia, of neutral ammonia, and of the NH2* radical.
-
Thermochemical Properties of the ammonia-water ionized dimer probed by ion-molecule reactions.
The journal of physical chemistry. A, 2005Co-Authors: Safwat Azeim, Guillaume Van Der RestAbstract:The Thermochemical Properties of some small clusters such as the (H2O)2•+ dimer have already been investigated by both experimental and theoretical methods. The recent method to selectively prepare the ammonia−water ionized dimer [NH3, H2O]•+ (and not its proton transfer isomer [NH4+, OH•]) allowed us to study its chemical reactivity. This study focuses on the charge and proton transfer pathways: Ion−molecule reactions in the cell of an FT-ICR mass spectrometer were carried out with a range of organic compounds. Examination of the reactivity of the [NH3, H2O]•+ ionized dimer versus ionization energy and proton affinity of the neutral reagents shows a threshold in the reactivity in both instances. This leads to a bracketing of Thermochemical Properties related to the dimer. From these experiments and in agreement with ab initio calculations, the adiabatic recombination energy of the [NH3, H2O]•+ dimer was evaluated at −9.38 ± 0.04 eV. The proton affinity bracketing required the reevaluation of two referen...
Chiung-chu Chen - One of the best experts on this subject based on the ideXlab platform.
-
Structure, Intramolecular Rotation Barrier, and Thermochemical Properties of Hydroxycyclohexadienyl Radical
The Journal of Physical Chemistry A, 2003Co-Authors: Chiung-chu Chen, Tsan H. Lay, Joseph W. BozzelliAbstract:Ab initio and density functional calculations are used to study the structures and Thermochemical Properties, Δ (T), S0(T), and Cp(T) (100 ≤ T/K ≤ 5000), of the benzene-OH adduct (hydroxycyclohexad...
-
Structures, Intramolecular Rotation Barriers, and Thermochemical Properties of Methyl Ethyl, Methyl Isopropyl, and Methyl tert-Butyl Ethers and the Corresponding Radicals
The Journal of Physical Chemistry A, 2003Co-Authors: Chiung-chu Chen, Joseph W. BozzelliAbstract:Structures and Thermochemical Properties, S°(T), and Cp(T) (50 ≤ T/K ≤ 5000) of three ethers and the corresponding radicals were determined by ab initio and density functional calculations. Molecul...