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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Providing theoretical data for detection of four formamidic acid isomers in astrophysical media

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Vichietti, R. M. [1] ; da Silva, A. B. F. [1] ; Haiduke, R. L. A. [1]
Total Authors: 3
[1] Univ Sao Paulo, Inst Quim Sao Carlos, Dept Quim & Fis Mol, CP 780, BR-13560970 Sao Carlos, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: MOLECULAR ASTROPHYSICS; v. 10, p. 1-10, MAR 2018.
Web of Science Citations: 1

We present a theoretical study, so that molecular data (geometrical parameters, vibrational frequencies, infrared intensities, electronic energies, enthalpies, and Gibbs energies) of four formamidic acid (FA) isomers (labeled here as FA1, FA2, FA3, and FA4) and formamide (HCONH2) are obtained from CCSD/ccpVTZ, CCSD/aug-cc-pVTZ, CCSD/cc-pVQZ, and CCSD(T)/cc-pVTZ calculations. Furthermore, on the basis of insufficient or even lacking theoretical and experimental results in the literature, we employed the aforementioned theory levels to determine benchmark values of dipole moments and rotational constants for these four FA isomers in order to contribute for their detection in astrophysical environments. Besides, we provide for the first time data about forward and reverse rate constants (200-4000 K) and Arrhenius' parameters for each interconversion reaction between pairs of FA isomers as well as for the tautomeric process involving FA4 and formamide, which were calculated from a Complete Basis Set (CBS) extrapolation equation obtained at CCSD/cc-pVTZ optimized geometries. Our kinetic analysis indicated a faster interconversion between the FA structures in comparison with the FA4 <-> HCONH2 process, suggesting that these isomers could co-exist in astrophysical media. Finally, we estimated that these isomers may be detected with relative abundances, {[}FA(x)]/{[}HCONH2] (x = 1, 2, 3, and 4), between similar to 0.01 and similar to 0.1% in astrophysical sources at chemical equilibrium conditions and temperatures around 10 0 0 K. However, these ratios can become as high as similar to 1, similar to 3, and similar to 5%, respectively, in hotter regions with temperatures around 20 0 0, 30 0 0, and 40 0 0 K (expected, for example, in massive star-forming regions). (C) 2018 Elsevier B.V. All rightsreserved. (AU)

FAPESP's process: 14/23714-1 - Electronic structure relativistic calculations for evaluation of new prolapse-free basis sets
Grantee:Roberto Luiz Andrade Haiduke
Support type: Regular Research Grants
FAPESP's process: 10/18743-1 - Employment of multipoles from the quantum theory of atoms in molecules and kinetic studies in systems found in the interstellar medium
Grantee:Roberto Luiz Andrade Haiduke
Support type: Regular Research Grants