A COMPARATIVE-STUDY OF THE PERFORMANCE OF DEWAR SEMIEMPIRICAL METHODSTO COMPUTE ELECTRON-SPIN-RESONANCE HYPERFINE COUPLING-CONSTANTS

The performance of Dewar's semiempirical methods MINDO/3, MNDO and AM 1 in computing electron spin resonance spectroscopy hyperfine coupling constants (hfcs) is assessed. A set of 32 molecules including neutral , cation and anion radicals were studied and the H, N and C nuclei wer e investigated. The linear relationship between hfcs and electronic sp in densities was analysed and the different correlation and dispersion coefficients used to assess the performance of the methods. Using the optimized geometries within each method, only MINDO/3 provides reliab le results for the three nuclei investigated. AM 1 and MNDO provide re asonable results only for N and C. However, when experimental geometri es are used, reasonable hfcs are obtained with the three methods for a ll the nuclei investigated.