We develop a theoretical model to predict the sublimation vapor pressure of pure substances. Moreover, we present a simple monoatomic molecule approximation, which reduces the complexity of the vapor pressure expression for polyatomic gaseous molecules at a convincing level of accuracy, with deviations of the Arrhenius prefactor for NaCl and NaF being 5.02% and 7.08%, respectively. The physical model is based on ab initio calculations, statistical mechanics, and thermodynamics. We illustrate the approach for Ni, Cr, Cu (metallic bond), NaCl, NaF, ZrO2 (ionic bond) and SiO2 (covalent bond). The results are compared against thermodynamic databases, which show high accuracy of our theoretical predictions, and the deviations of the predicted sublimation enthalpy are typically below 10%, for Cu even only 0.1%. Furthermore, the partial pressures caused by gas phase reactions are also explored, showing good agreement with experimental results.
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http://dx.doi.org/10.3390/ma16072826 | DOI Listing |
Nat Commun
January 2025
Department of Chemistry, Michigan State University, East Lansing, Michigan, USA.
The formation of following the double ionization of small organic compounds via a roaming mechanism, which involves the generation of H and subsequent proton abstraction, has recently garnered significant attention. Nonetheless, a cohesive model explaining trends in the yield of characterizing these unimolecular reactions is yet to be established. We report yield and femtosecond time-resolved measurements following the strong-field double ionization of CHX molecules, where X = OD, Cl, NCS, CN, SCN, and I.
View Article and Find Full Text PDFJ Mol Model
January 2025
School of Chemistry & Chemical Engineering, Linyi University, Linyi, 276000, China.
Context: In this work, a comparative study on the catalytic conversion of 5-hydroxymethyl furfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) on precious Pd(111) and nonprecious Cu(111) was systematically performed. On the basis of the calculated activation energy (E) and reaction energy (E), the optimal energy path for the hydrogenation of HMF (F-CHO) into BHMF (F-CHOH) on Pd(111) is as follows: F-CHO + 2H → F-CHOH + H → F-CHOH; the minimum reaction path on Cu(111) is F-CHO + 2H → F-CHO + H → F-CHOH. On Cu(111), the formation of F-CHOH from F-CHO hydrogenation is the rate-determining step because it has the highest reaction energy barrier and the smallest rate constant.
View Article and Find Full Text PDFChem Sci
January 2025
Radioisotope Science and Technology Division, Oak Ridge National Laboratory Oak Ridge TN 37830 USA
Lanthanides (Ln) are typically found in the +3 oxidation state. However, in recent decades, their chemistry has been expanded to include the less stable +2 oxidation state across the entire series except promethium (Pm), facilitated by the coordination of ligands such as trimethylsilylcyclopentadienyl, CHSiMe (Cp'). The complexes have been the workhorse for the synthesis and theoretical study of the fundamental aspects of divalent lanthanide chemistry, where experimental and computational evidence have suggested the existence of different ground state (GS) configurations, 4f or 4f 5d, depending on the specific metal.
View Article and Find Full Text PDFACS Omega
December 2024
Faculty of Health Science, University of Ss. Cyril and Methodius, 91701 Trnava, Slovakia.
Nat Commun
January 2025
Institute for Materials Science, University of Stuttgart, D-70569, Stuttgart, Germany.
The knowledge of diffusion mechanisms in materials is crucial for predicting their high-temperature performance and stability, yet accurately capturing the underlying physics like thermal effects remains challenging. In particular, the origin of the experimentally observed non-Arrhenius diffusion behavior has remained elusive, largely due to the lack of effective computational tools. Here we propose an efficient ab initio framework to compute the Gibbs energy of the transition state in vacancy-mediated diffusion including the relevant thermal excitations at the density-functional-theory level.
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