Q. How to study hyperfine splitting constants (hfsc) with the SAC-CI method.

 

A. The basis sets should be double or triple zeta quality for describing K-shell orbital, augmented with polarization functions. The STO-GTO expansion method is useful for including the cusp condition of the wave function at nucleus. (See, J. Chem. Phys. 91, 6205 (1989))

  All single and double excitation operators are included in the SAC-CI wave function, and the perturbatoin selection is not performed. This is to avoid selecting out the configurations that are necessary to calculate hfsc. Configurations important for properties are not necessarily give significant contributions to the correlation energy.