Highly accurate Gaussian basis sets for low-lying excited states of some positive and negative ions

The improved generator coordinate Hartree-Fock (HF) method has been used to generate highly accurate Gaussian basis sets for low-lying excited states of some mono-positive and -negative ions. From these basis sets, total HF energies have been calculated and compared with results reported in the literature. The accuracy of HF energy achieved herein is the best so far obtained with finite basis set expansion of Gaussian-type functions (GTFs). Using GTFs, difference between corresponding energies calculated with our sets and those reported in the literature is achieved up to 13.8 mhartree.