The origin of 1560 cm−1 band in experimental IR spectra of water adsorbed on TiO2 surface: Ab initio assessment

2016 ◽  
Vol 662 ◽  
pp. 97-101 ◽  
Author(s):  
Ruslan Kevorkyants ◽  
Aida V. Rudakova ◽  
Yuri V. Chizhov ◽  
Kirill M. Bulanin
Keyword(s):  
Ir Spectra ◽  
Ab Initio ◽  
Tio2 Surface ◽  
Experimental Ir

The Structure of Lithiated Aminonitriles in Solution: Interpretation of their Experimental IR Spectra by Means of ab initio Calculations

1991 ◽  
Vol 46 (3) ◽  
pp. 275-288 ◽  
Author(s):  
Gerhard Raabe ◽  
Elke Zobel ◽  
Jörg Fleischhauer ◽  
Pete Gerdes ◽  
Dietrich Mannes ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Ab Initio ◽  
Acetyl Chloride ◽  
Cyano Group ◽  
Semiempirical Method ◽  
Vibrational Frequencies ◽  
Hydrogen Atoms ◽  
Model Compounds ◽  
Experimental Ir ◽  
Semiempirical Mndo

AbstractQuantum chemical calculations of relative energies and vibrational frequencies have been performed in order to elucidate the structure of metalated aminonitriles (1R2RN)3RC2NLi formed upon lithiation of (1R2RN)3RCH-CN in tetrahydrofuran at -78 °C. For the sake of feasibility the calculations have been performed on model compounds where the heavy substituents 1R, 2R and 3R and in some cases even the complete amino group (1R2RN) and 3R have been replaced by hydrogen atoms. In the gasphase a lithium-bridged (nonclassical) monomer, whose lithium atom is within bonding distance to the atoms of the cyano group and the adjacent carbon atom, was found to be about 9 kcal/mol lower in energy than the most stable isomer of the corresponding nitrogen metalated ketenimine with amost linear CNLi moiety. However, the relative stability of the two structures will most likely be reversed under the influence of a solvent (modeled by H20). Dimerization of H2C2NLi, yielding a product of D2h symmetry with a four-membered (LiN)2 ring, turned out to be exothermic by about 41 kcal/mol in the gasphase and 15 kcal/mol when the model solvent is present. While in the case of the lithiated amino ketenimine with almost linear CNLi segment the structure obtained with the semiempirical MNDO method widely parallels the ab initio results, the semiempirical method seems to perform less reliably for the nonclassical monomer. Formation of the trapping products obtained with methyl iodide and acetyl chloride is explained in terms of orbital- and charge control, respectively. According to this analysis, the results of trapping experiments are compatible with presence of a dimer, of a monomer with almost linear CNLi moiety, or of a monomer with lithium in a bridging position. However, comparison of observed and computed vibrational frequencies and of the calculated energies of classical and nonclassical structures led to the conclusion that the observed IR spectra are not due to nonclassical molecules with lithium in a bridging position. Taking into account the results of recent cryoscopic measurements we assign the characteristic absorptions in the experimental IR spectra to keteniminelike monomers and their dimers

scholarly journals Theoretical Investigations on the Reactivity of Methylidyne Radical toward 2,3,7,8-Tetrachlorodibenzo-p-Dioxin: A DFT and Molecular Dynamics Study

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2685 ◽  
Author(s):  
Weihua Wang ◽  
Wenling Feng ◽  
Wenliang Wang ◽  
Ping Li
Keyword(s):  
Molecular Dynamics ◽  
Ir Spectra ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Ab Initio Molecular Dynamics ◽  
Hyperfine Coupling Constants ◽  
Dynamics Simulations ◽  
Ch Radical

To explore the potential reactivity of the methylidyne radical (CH) toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the reaction mechanism between them has been systematically investigated employing the density functional theory (DFT) and ab initio molecular dynamics simulations. The relevant thermodynamic and kinetic parameters in the possible reaction pathways have been discussed as well as the IR spectra and hyperfine coupling constants (hfcc’s) of the major products. Different from the reaction of the CH radical with 2,3,7,8-tetrachlorodibenzofuran, CH radical can attack all the C-C bonds of TCDD to form an initial intermediate barrierlessly via the cycloaddition mechanism. After then, the introduced C-H bond can be further inserted into the C-C bond of TCDD, resulting in the formation of a seven-membered ring structure. The whole reactions are favorable thermodynamically and kinetically. Moreover, the major products have been verified by ab initio molecular dynamics simulations. The distinct IR spectra and hyperfine coupling constants of the major products can provide some help for their experimental detection and identification. In addition, the reactivity of the CH radical toward the F- and Br-substituted TCDDs has also been investigated. Hopefully, the present findings can provide new insights into the reactivity of the CH radical in the transformation of TCDD-like dioxins.

Quantum and classical IR spectra of (HCOOH)2, (DCOOH)2 and (DCOOD)2 using ab initio potential energy and dipole moment surfaces

2018 ◽  
Vol 212 ◽  
pp. 33-49 ◽  
Author(s):  
Chen Qu ◽  
Joel M. Bowman
Keyword(s):  
Dipole Moment ◽  
Potential Energy ◽  
Ir Spectra ◽  
Ab Initio ◽  
Ir Spectrum ◽  
Quantum Calculation

Full-dimensional (24 modes) quantum calculation of the IR spectrum of (DCOOD)2, and comparison with classical MD one.

scholarly journals Prediction of the near-IR spectra of ices by ab initio molecular dynamics

2019 ◽  
Vol 21 (18) ◽  
pp. 9433-9440 ◽  
Author(s):  
Rafael Escribano ◽  
Pedro C. Gómez ◽  
Belén Maté ◽  
Germán Molpeceres ◽  
Emilio Artacho
Keyword(s):  
Molecular Dynamics ◽  
Ir Spectra ◽  
Ab Initio ◽  
Ab Initio Molecular Dynamics ◽  
Near Ir

Use of ab initio molecular dynamics to predict the near-IR spectra of ices and application to astronomical models.

An ab initio study of conformations and IR spectra of 5-substituted 1,3-cyclopentadienes

2003 ◽  
Vol 81 (1) ◽  
pp. 14-30 ◽  
Author(s):  
Cory C Pye ◽  
James D Xidos ◽  
D Jean Burnell ◽  
Raymond A Poirier
Keyword(s):  
Ir Spectra ◽  
Ab Initio ◽  
Computational Study ◽  
Vibrational Frequencies ◽  
Ab Initio Study ◽  
Group 14

A computational study of 5-substituted cyclopentadienes is presented. The substituents considered are the group 14–17 elements of the second through fifth periods, saturated by hydrogens as needed to fulfill normal valence requirements. The conformational characteristics are examined and rationalized using bond–antibond interactions and steric arguments. Trends in vibrational frequencies are discussed and compared with experiment where possible.Key words:cyclopentadiene, ab initio, spectra.

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