  We analyze the quantum-mechanical rotational excitation/de-excitation
spectrum and cross sections of CN molecules during low and high-energy
collisions with protons, H+. The problem is of significant importance in
astrophysics of the early Universe, specifically connected with the problems of
cosmic microwave background (CMB) radiation. A quantum-mechanical
close-coupling method is applied in this work. The cyanide molecule (CN) is
treated as a rigid rotor, i.e. the distance between the carbon and nitrogen
atoms is fixed at an average equilibrium value. The new results of the
excitation/de-excitation cross-sections and corresponding thermal rate
coefficients are compared with the results of few previous calculations
performed on the basis of few approximate semiclassical frameworks. The
interaction potential between CN and H+ is taken in the following form: proton
induced polarization potential + proton-dipole potential + proton-quadrupole
potential.
