Dear CCLers ; I have a problem in calculating hyperfine coupling constants of formaldehyde radical cation using MOPAC. But the result show only following part for hyperfine coupling constants. HYPERFINE COUPLING COEFFICIENTS H 1 0.17398 C 2 -0.00748 O 3 0.00326 H 4 0.17398 I cannot understand those numbers and what units. If you have any idea on this matter I'd appreciate it. Ohyun Kwon Department of Chemistry Auburn University Auburn, AL 36849