Even numbered carbon clusters: cost-effective wavefunction-based method for calculation and automated location of most structural isomers

Abstract

Using second-order Moller-Plesset perturbation-theoretic calculations with extrapolation of the energy from the lowest steps of the hierarchical staircase to the complete basis set limit, a wave function-based approach emerges that rivals density functional theory in accuracy and cost-effectiveness. Tested on a large set of reactions, the method is now applied to the carbon clusters. Combined with variable-scaling opposite spin theory, the results approximate couple-cluster quality at no additional cost. Jointly with a stimulated breakup of the molecule by choosing a (simple or composite) driving coordinate at an adequate level of theory, the approach still offers a near automated tool for locating structural isomers along the optimized reaction coordinate for stimulated evolution so obtained. Adaptations are also suggested.