Accurate ab initio potential of CO(X1Σ+) at low cost via correlation scaling and extrapolation method

The potential energy curve (PEC) for the ground state of CO(X1Σ+) has been investigated by the highly accurate valence internally contracted multi-reference configuration interaction with the Davidson correction (MRCI+Q) method in combination with a series of correlation-consistent basis sets of Dunning and co-workers. The scheme proposed by Varandas, which enables high-quality molecular potentials to be obtained from small basis set calculations via scaling and extrapolation of the electron correlation to the complete basis set limit plus extrapolation to the complete basis set limit of the complete-active-space self-consistent field energy, has been applied to the system under consideration here. The present results are compared with the other theoretical and experimental data, and show that the present methods are credible and accurate.

► The PEC of CO(X1Σ+) is calculated accurately. ► The spectroscopic constants of CO(X1Σ+) are calculated more accurately. ► The Vibrational manifolds of CO(X1Σ+) are investigated.