Non-adiabatic interactions in H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si18.svg" display="inline" id="d1e471"><mml:msup><mml:mrow/><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> + C<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si17.svg" display="inline" id="d1e479"><mml:msub><mml:mrow/><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:math> system: An ab initio study

and, Pooja Chahal; Kumar, T. J. Dhilip

doi:10.1016/j.chemphys.2023.111941

Cited by 3 publications

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“…16 In addition, numerous other pure carbon clusters have also been detected in the ISM, with the chain length as small as two (C 2 ) and as large as seventy (C 70 ). 8 The smallest species, C 2 , was detected via electronic spectroscopy back in 1977, 2 while the two other symmetric species, C 3 17–19 and C 5 , 20,21 were detected using ro-vibrational spectroscopy a decade later.…”

Section: Introductionmentioning

confidence: 99%

Quantum rotational dynamics of l-C₄(³Σ−g) by H₂ at low temperatures employing a machine learning augmented potential energy surface

Chahal,

Kushwaha,

Dhilip Kumar

2024

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 99%

Quantum rotational dynamics of l-C₄(³Σ−g) by H₂ at low temperatures employing a machine learning augmented potential energy surface

Chahal,

Kushwaha,

Dhilip Kumar

2024

Phys. Chem. Chem. Phys.

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Quantum rotational dynamics of linear C5 at low interstellar temperatures for H2 collision

Chahal,

Kushwaha,

Dhilip Kumar

2024

The Journal of Chemical Physics

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The quantum dynamics of carbon chains through H2 and He collisions in the interstellar medium (ISM) is an important step toward accurate modeling of their abundance in non-local thermodynamic equilibrium conditions. The C5(Σg+1) molecule is the longest pure carbon chain detected in the ISM to date. While He collisions are computationally easy to perform, the collision with much more abundant H2 is both complicated and computationally demanding. Using templates for approximating p-H2 collisional rates, such as scaling He rates and using a reduced 4D → 2D potential energy surface (PES), has limited applicability. On the other hand, any such approximation does not exist for o-H2. Therefore, a full rotational dynamics of C5 with both p- and o-H2 is performed considering both molecules as rigid-rotors. The PES is calculated using CCSD(T)-F12a/AVTZ, and a neural network fitting model has been carefully chosen to strictly obey spectroscopic accuracy and augment the PES. The augmented PES is then expanded into radial terms using the bispherical harmonics function, and close coupling calculations have been done to get the cross sections and, subsequently, rate coefficients for various rotational transitions of C5.

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Inelastic scattering of PO+ by H2 at interstellar temperatures

Chahal,

Kushwaha,

Dhilip Kumar

2024

Monthly Notices of the Royal Astronomical Society

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Phosphorous species are of great interest in interstellar chemistry since they are the basic blocks for building life here on Earth. Modelling the abundance and environment of recently detected PO+ under non Local Thermodynamic Equilibrium (LTE) requires rotational spectra of the molecule along with accurate collisional rates with the most abundant species, hydrogen and helium. A new 4D ab initio potential energy surface (PES) of PO+ - H2 collision is calculated using CCSD(T)/CBS(DTQ) methodology considering rigid rotor approximation. The region containing the minima of the PES is augmented using neural networks (NN) model while very high potentials (>2500 cm−1) and asymptotic region have been approximated using Slater and R−4 functions respectively. The close coupling calculations have been performed using MOLSCAT software for both ortho and para-H2. The rate coefficients have been reported for transitions j − j′ = 1 − 0, 2 − 1, 3 − 2 and 5 − 4 through which PO+ has been experimentally detected in ISM. The rate coefficients for even and odd transitions of PO+ with para-H2 are compared with that of helium and are found to be 1.1-2.0 times higher. For even transitions (Δj = 2), the ortho-H2 rates are 10% higher than para-H2 rates. However, the trend reverses in the case of odd transitions (Δj = 1) when higher J transitions are considered at low temperatures. At higher temperatures, the ortho rates cross the para-H2 rates and become larger than the latter. The new rate coefficients with both ortho and para-H2 will enable accurate modelling of the PO+ abundance in the interstellar medium under non-LTE conditions.

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Non-adiabatic interactions in H+ + C3 system: An ab initio study

Cited by 3 publications

References 35 publications

Quantum rotational dynamics of l-C₄(³Σ−g) by H₂ at low temperatures employing a machine learning augmented potential energy surface

Quantum rotational dynamics of l-C₄(³Σ−g) by H₂ at low temperatures employing a machine learning augmented potential energy surface

Quantum rotational dynamics of linear C5 at low interstellar temperatures for H2 collision

Inelastic scattering of PO+ by H2 at interstellar temperatures

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Non-adiabatic interactions in H+ + C3 system: An ab initio study

Cited by 3 publications

References 35 publications

Quantum rotational dynamics of l-C4(3Σ−g) by H2 at low temperatures employing a machine learning augmented potential energy surface

Quantum rotational dynamics of l-C4(3Σ−g) by H2 at low temperatures employing a machine learning augmented potential energy surface

Quantum rotational dynamics of linear C5 at low interstellar temperatures for H2 collision

Inelastic scattering of PO+ by H2 at interstellar temperatures

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Quantum rotational dynamics of l-C₄(³Σ−g) by H₂ at low temperatures employing a machine learning augmented potential energy surface

Quantum rotational dynamics of l-C₄(³Σ−g) by H₂ at low temperatures employing a machine learning augmented potential energy surface