New rotational rate coefficients computation of the linear NaC3N(<i>X</i>1Σ+) by collision with He(1S) and astrophysical implication

Abstract

ABSTRACT For a better understanding of the physico-chemistry in the interstellar medium, collisional data are needed. In this work, we provide rate coefficients for the recently detected by Cabezas and collaborators in 2023 sodium cyanoacetylide molecule NaC$_{3}$N($X^{1}\Sigma ^{+}$) induced by collisions with He. A new two-dimensional potential energy surface (2D-PES) is derived by adopting the high-level theory of the explicitly correlated coupled cluster with single, double, and perturbative triple excitations (CCSD(T)-F12) in conjunction with the aug-cc-pVTZ basis sets. Our 2D-PES presents two minima: the global one with a well depth of $-86.58$ cm$^{-1}$ and the second well with a $-47.01$ cm$^{-1}$ depth. This was expected by the Natural Bond Orbital analysis showing two electrophilic zones located on Na and N linked Carbon with respective atomic charges : $+0.96575$ and $+0.28910$. This PES was used to calculate inelastic cross-sections within the framework of the close-coupling theory for total energies $\le 170$ cm$^{-1}$ and $J\le 22$. Using the Maxwell–Boltzmann distribution of kinetic energies, these cross-sections were integrated to generate the collisional (de)-excitation rate coefficients for temperatures below 30 K. In order to estimate the impact of the computed collisional rates, a non-local thermodynamical equilibrium radiative transfer calculation was performed. The new collisional data can allow accurate NaC$_{3}$N abundance determination in the interstellar medium.