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Volume 9
Chemical Sciences Journal
Asia Chemistry 2018
September 12-13, 2018
11
th
Annual Congress on
September 12-13, 2018 Singapore
Chemistry
Rotational excitation of the CP(Χ
2
Σ
+
) open shell molecule due to Collision with He(
1
S)
Cheikh Tidiane Bop
Cheikh Anta Diop University, Senegal
P
hosphorus bearing molecules have been discovered in the circumstellar and interstellar media. Modeling their abundance
accurately requires computations of rate coefficients induced by collision with He and H
2
(i.e., the most abundant gaseous
components). Without these data along with radiative transitions, astrophysicists would assume the Local Thermodynamic
Equilibrium (LTE) which is rarely verified in space. Rate coefficients may be computed by first determining highly accurate
Potential Energy Surface (PES) and cross sections. Here, we present the first PES of the CP(X
2
Σ
+
)-He(
1
S) Van Der Waals
collisional complex. The ab initio interaction potential was performed using the explicitly correlated restricted coupled
cluster approach with simple, double, and perturbative triple excitation (RCCSD(T)-F12) in connection with the augmented
correlation consistent polarized valence triple-ζ Gaussian basis set (aug-cc-pVTZ), as implemented in the Molpro program.
The potential presents two minima of -18.62 cm
-1
and -18.72 cm
-1
. From the PES obtained, we have computed state-to-state
excitation cross sections of CP due to collision with He for energies up to 500 cm
-1
. Rotational transitions involving the fine-
structure levels of the CP molecule were treated with a Recoupling Technique based on the scattering matrix calculated with
the exact quantum mechanical close coupling method implemented in the Molscat code. Discussions on the propensity rules
between the fine-structure levels were made and we found that the Δj=ΔN transitions are favored with respect to the Δj≠ΔN
ones. The data presented here may have a great impact on the accurate determination of the CP abundance in space. This would
yield a better understanding of the phosphorous interstellar chemistry. Indeed, carbon phosphorus is expected to originate
from HCP photo-dissociation and it is thought to be the main precursor of CCP formation.
cheikhtidiane.bop@ucad.edu.snChem Sci J 2018, Volume 9
DOI: 10.4172/2150-3494-C5-030