Thermochemical properties of gas-phase MgOH and MgO determined by Fourier transform mass spectrometry

Operti, Lorenza; Tews, E. C.; MacMahon, Timothy J.; Freiser, Ben S.

doi:10.1021/ja00208a002

Cited by 90 publications

(48 citation statements)

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“…footnotes in Table 8). Later, an experimental thermodynamic dissociation energy (all atoms in their ground states) was found in the literature [44], which is in accordance with B3LYP as well as the ACPF calculations. Thus, the MgO problem is solved.…”

Section: Concluding Remarks On Calculated Versus Experimental Propertsupporting

confidence: 81%

Quantum chemical B3LYP/cc-pvqz computation of ground-state structures and properties of small molecules with atoms of Z ≤ 18 (hydrogen to argon)(IUPAC Technical Report)

Janoschek

2001

Pure and Applied Chemistry

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Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgmentAbstract: Since density functional theory (DFT) achieved a remarkable breakthrough in computational chemistry, the important general question "How reliable are quantum chemical calculations for spectroscopic properties?" should be answered anew. In this project, the most successful density functionals, namely the Becke B3LYP functionals, and the correlation-consistent polarized valence quadruple zeta basis sets (cc-pvqz) are applied to small molecules. In particular, the complete set of experimentally known diatomic molecules formed by the atoms H to Ar (these are 214 species) is uniformly calculated, and calculated spectroscopic properties are compared with experimental ones. Computationally demanding molecules, such as open-shell systems, anions, or noble gas compounds, are included in this study. Investigated spectroscopic properties are spectroscopic ground state, equilibrium internuclear distance, harmonic vibrational wavenumber, anharmonicity, vibrational absolute absorption intensity, electric dipole moment, ionization potential, and dissociation energy. The same computational method has also been applied to the ground-state geometries of 56 polyatomic molecules up to the size of benzene. Special sections are dedicated to nuclear magnetic resonance (NMR) chemical shifts and isotropic hyperfine coupling constants. Each set of systems for a chosen property is statistically analyzed, and the above important question "How reliable...?" is mathematically answered by the mean absolute deviation between calculated and experimental data, as well as by the worst agreement. In addition to presentation of numerous quantum chemically calculated spectroscopic properties, a corresponding updated list of references for experimentally determined properties is presented.

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Section: Concluding Remarks On Calculated Versus Experimental Propertsupporting

confidence: 81%

Quantum chemical B3LYP/cc-pvqz computation of ground-state structures and properties of small molecules with atoms of Z ≤ 18 (hydrogen to argon)(IUPAC Technical Report)

Janoschek

2001

Pure and Applied Chemistry

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“…While both pseudopotentials give excellent agreement to the experimental bond length and electron affinity, we find some difference for the binding energy and the ionization energy. Using a He-core, rather than Ne-core, pseudopotential for Mg increases the molecular binding energy from 2.28±0.01 eV to 2.43±0.01 eV, in comparison to the experimental value of 2.54±0.22 eV [19,[46][47][48]. This suggests that allowing the Mg 2s and 2p electrons to participate in the bonding allows more recovery of the binding energy.…”

Section: Supplementary Information I Properties Of Mgo Molecule As Dmentioning

confidence: 75%

Point-defect optical transitions and thermal ionization energies from quantum Monte Carlo methods: Application to theF-center defect in MgO

2013

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We present an approach to calculation of point defect optical and thermal ionization energies based on the highly accurate quantum Monte Carlo methods. The use of an inherently many-body theory that directly treats electron correlation offers many improvements over the typically-employed density functional theory Kohn-Sham description. In particular, the use of quantum Monte Carlo methods can help overcome the band gap problem and obviate the need for ad-hoc corrections. We demonstrate our approach to the calculation of the optical and thermal ionization energies of the F-center defect in magnesium oxide, and obtain excellent agreement with experimental and/or other high-accuracy computational results.From electronics to optoelectronics to photovoltaics, point defects influence and even dominate the properties of semiconducting materials [1][2][3][4][5][6]. Quantitative descriptions of the effect of point defects on electronic, optical, and transport properties is critical to enabling point-defect engineering for materials design. However, accurate prediction of point-defect energetics, thermal ionization energies, and optical transition energies from first principles remains a challenge. Currently, the most widely-used approach based on conventional density functional theory (DFT) suffers from poor descriptions of band gaps that render difficult the accurate description of mid-gap defect states [5,[7][8][9]]. Here we demonstrate that, by contrast, an inherently many-body approach based on quantum Monte Carlo (QMC) methods [10,11] can eliminate these problems and enable high-accuracy calculations of point defect optical and thermal ionization energies. Our computed optical transition energies are in excellent agreement with experimental and/or other highaccuracy computational results for the same system [12], and demonstrate that QMC can obtain quantitatively accurate descriptions.

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“…1 Unlike the earlier report by Freiser et al, 9 who found Mg + to be the only ionic product, these authors observed several dissociation channels leading to the formation of Mg + , CH 3 + , MgO + , and MgOH + . The last product is difficult to ascertain because of the overlap of the isotope peaks of 25 Mg and 26 Mg in the mass spectrum. Farrar and co-workers studied Sr + (CH 3 OH) and Sr + (CH 3 OD) using the photodissociation method.…”

Section: Introductionmentioning

confidence: 99%

Reactions of Alkaline Earth Metal Ions with Methanol Clusters

Yang

1998

J. Phys. Chem. A

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The gas phase reactions between singly charged alkaline earth metal ions (Mg + , Ca + , Sr + and Ba + ) and methanol clusters are studied in a pick-up cluster source. In much the same way as for the alkaline earth metal ion-water cluster systems studied by Fuke et al. (J. Am. Chem. Soc. 1995, 117, 747), anomalous product distributions were observed that are characterized by two product switching regions. The first product switching from M + (CH 3 OH) n to MOCH 3 + (CH 3 OH) n-1 occurs for n at around 5. The MOCH 3 + (CH 3 OH) n-1 species switches back to Mg + (CH 3 OH) n for n at around 15 (second switching). The critical sizes for the first and the second switching were found to be affected by the metal and deuterium substitutions. Ab initio calculations on the structures and energetics of the reactants and products were carried out to facilitate the interpretation of the product switching behaviors.

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Thermochemical properties of gas-phase MgOH and MgO determined by Fourier transform mass spectrometry

Cited by 90 publications

References 0 publications

Quantum chemical B3LYP/cc-pvqz computation of ground-state structures and properties of small molecules with atoms of Z ≤ 18 (hydrogen to argon)(IUPAC Technical Report)

Quantum chemical B3LYP/cc-pvqz computation of ground-state structures and properties of small molecules with atoms of Z ≤ 18 (hydrogen to argon)(IUPAC Technical Report)

Point-defect optical transitions and thermal ionization energies from quantum Monte Carlo methods: Application to theF-center defect in MgO

Reactions of Alkaline Earth Metal Ions with Methanol Clusters

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