Abstract:
The objective of this study is to enhance our understanding of the existence of molecules in interstellar
space by determining the collisional rate coefficients with the most prevalent species. The study
examines the impact of para-H2 collisions, specifically when it is in its ground vibrational state with a
nuclear spin of para-H2, i.e., jp = 0, on causing the rotational deexcitation of the diisocyanogen (CNNC)
molecule. These scattering data are obtained as a result of spherically averaging a four-dimensional
potential energy surface (4DPES) over the H2 orientations. Using the CCSD(T)-F12a approach and augcc-pVTZ basis sets, the ab initio 4DPES for the CNNC–H2 van der Waals system is calculated. The
CNNC–para-H2 4DPES attains a global minimum of 221.38 cm 1 at the CNNC and H2 center of mass
distance (R) of 3.1 Å. The method of close coupling calculations is employed for the purpose of calculating the cross-sectional data of CNNC with para-H2 ( jp = 0), for total energies up to 1000 cm 1
. Rate
coefficients are computed over the temperature range of 1 K to 100 K. Propensity suggests that even
Dj transitions are strongly preferred. The rate coefficients for CNNC–H2 are determined to be
0.90–2.95 times those of CNNC–He, which implies it is not reliable to estimate the H2 rate coefficients
by multiplying the rate coefficients for CNNC–He collision with a scaling factor of 1.38.
