Rotational de-excitation of N-protonated isocyanic acid (H2NCO+) by collision with He atoms

Abstract

ABSTRACT Isocyanic acid protonated at nitrogen (H$_2$NCO$^+$) can help to understand the chemistry of [C,H,N,O] isomeric family as well as the determination of their abundance in the Sgr B2(N) and low-mass protostar L483 regions. New three-dimensional potential energy surface (3D-PES) for H$_2$NCO$^+$-He complex was constructed. The ab initio 3D-PES was computed by the use of explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation (CCSD(T)-F12a) with augmented-correlation consistent-polarized valence triple zeta (aug-cc-pVTZ) Gaussian basis set. A global minimum with a well depth of 238.95 cm$^{-1}$ located at ($\Phi$ = 90$^\circ$, $\theta$ = 95$^\circ$, and R = 5.2 bohr) was observed. Rotational cross-sections were calculated for total energy up to 1000 cm$^{-1}$ using coupled states approach. Thermal rate coefficients were estimated until temperature of 200 K. Propensity rules favouring $|\Delta J| = |\Delta K_c| = 1$ with $|\Delta K_a|$ = 0 transitions were found for both para and ortho-H$_2$NCO$^+$.