Fixed-node diffusion Monte Carlo simulation of small ionized carbon clusters

The structural and energetic features of small cationic carbon clusters with up to ten atoms are investigated using the Hartree-Fock, density functional theory, and fixed-node diffusion Monte Carlo simulations. The results show that the cationic carbon clusters present significant structural changes with relevant Jahn-Teller distortion compared to the neutral ones. A satisfactory agreement with available experimental results is observed for ionization potential, relative binding energy, and atomic dissociation energy. Our calculations present quantitative investigations on the electron correlation effects in the cationic carbon clusters and show the important roles of the electron correlation in the stability of these clusters.