Numerical multiconfiguration self-consistent-field study of the hyperfine structure in the infrared spectrum of ³He⁴He⁺

Numerical multiconfiguration self-consistent-field (MCSCF) procedure is employed to calculate the hyperfine interaction energy for the ³He⁴He⁺ cation at different internuclear separations. A conventional vibrational averaging of the energy allows the calculation of hyperfine splitting in the IR spectrum. This is done for several of the lowest vibrational states. We predict that the hyperfine splitting will get larger with the increasing vibrational excitation. Various different MCSCF wave functions are used in the study to verify the convergence of the hyperfine parametes and to determine the importance of the electronic correlation.