Volume 45, Issue 32 pp. 2793-2804
RESEARCH ARTICLE

Energy and spectroscopic parameters of neutral and cations isomers of the CnH2 (n = 2–6) families using high-level ab-initio approaches

Lenin J. Díaz Soto

Corresponding Author

Lenin J. Díaz Soto

Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, CT, Rio de Janeiro, Brazil

Correspondence

Lenin J. Díaz Soto, Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, CT, Bloco A, Rio de Janeiro 21949-900, Brazil.

Email: [email protected]

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Ricardo R. Oliveira

Ricardo R. Oliveira

Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, CT, Rio de Janeiro, Brazil

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Leonardo Baptista

Leonardo Baptista

Departamento de Química e Ambiental, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Resende, Brazil

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Enio F. da Silveira

Enio F. da Silveira

Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, Brazil

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Marco Antonio Chaer Nascimento

Marco Antonio Chaer Nascimento

Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, CT, Rio de Janeiro, Brazil

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First published: 23 August 2024
Citations: 3

Abstract

Cationic species, previously detected from ion-induced desorption of solid methane by plasma desorption mass spectrometry (PDMS), and neutral species, are investigated using high-level ab-initio approaches. From a set of 25 cationic and 26 neutral structures belonging to CnH2 (n = 2–6) families, it was obtained the energy, rotational constants, harmonic vibrational frequency, charge distribution and excitation energies. The ZPVE-corrected energies, at CCSD(T)-F12; CCSD(T)-F12/RI/(cc-pVTZ-F12, cc-pVTZ-F12-CABS, cc-pVQZ/C) (n = 2–5) and CCSD(T)/cc-pVTZ (n = 6) levels, reveal that the topology of the most stable isomer vary with n and the charge. Out of 674 harmonic frequencies, those with maximum intensity are generally in the 3000–3500 cm−1 range. Analysis of 169 vertical transition energies calculated with the EOM-CCSD approach, suggest three C6H2 species as potential carriers of the diffuse interstellar bands (DIB). Systematic comparison of properties between neutral and cationic species can assist in the structural description of complex matrices.

DATA AVAILABILITY STATEMENT

The data that supports the findings of this study are available in the supplementary material of this article.

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