MULTICONFIGURATIONAL SELF-CONSISTENT-FIELD CALCULATIONS OF NUCLEAR SHIELDINGS USING LONDON ATOMIC ORBITALS

Nuclear shielding calculations are presented for multiconfigurational self-consistent field wave functions using London atomic orbitals (gau ge invariant atomic orbitals). Calculations of nuclear shieldings for eight molecules (H2O, H2S, CH4, N-2, CO, HF F-2, and SO2) are presente d and compared to corresponding individual gauges for localized orbita ls (IGLO) results. The London results show better basis set convergenc e than IGLO, especially for heavier atoms. It is shown that the choice of active space is crucial for determination of accurate nuclear shie lding constants.