The basic approximation of the MNDO method is applied to the SCF-MO theory of nu- clear magnetic shielding constants.Gauge-invariant atomic orbitais(GIAO)and derived equations are used to cal- culate NMR chemical shif...The basic approximation of the MNDO method is applied to the SCF-MO theory of nu- clear magnetic shielding constants.Gauge-invariant atomic orbitais(GIAO)and derived equations are used to cal- culate NMR chemical shifts.A more simple and effective calculation of integration for operators 1/r_M,L_M and L_M/r_M described in our previous paper is used.By proper selection of MNDO parameters together with the two-center approximation,a satisfactory agreement between computational and experimental ^(13)C and ^(19)F chemi- cal shifts is obtained for a representative set of fluorides.展开更多
文摘The basic approximation of the MNDO method is applied to the SCF-MO theory of nu- clear magnetic shielding constants.Gauge-invariant atomic orbitais(GIAO)and derived equations are used to cal- culate NMR chemical shifts.A more simple and effective calculation of integration for operators 1/r_M,L_M and L_M/r_M described in our previous paper is used.By proper selection of MNDO parameters together with the two-center approximation,a satisfactory agreement between computational and experimental ^(13)C and ^(19)F chemi- cal shifts is obtained for a representative set of fluorides.
