Abstract:
New ab initio potential energy surfaces have been generated for
the ground state and low-lying excited states of the H+ + C3 system using the
multireference configuration interaction (MRCI) method with Dunning’s augmented
correlation consistent polarized valence quadruple-zeta (aug-cc-pVQZ)
basis sets. The ground state and low-lying excited states show avoided crossing,
indicating nonadiabatic coupling. The anisotropy of the ground-state surface has
been analyzed by computing the multipolar expansion coefficients with the
frozen C−C equilibrium bond length. The asymptotic potential has been merged
with the interaction potential by spline fit. This potential is then used in the full
close coupling calculations of rotational excitation in C3 collision with the proton
for rotational levels j = 0, 2, 4, 6, 8 at very low collision energy. By averaging the
cross sections over a Boltzmann distribution of velocities of the incoming atom,
we obtain and discuss corresponding rate coefficients of C3 collision with the
proton in the interstellar medium.
