an ab initio study of metalated cmp,ump& dtmp at hf level:bond energies and isotropic nmr shielding of atoms

the interaction of magnesium hydrate at the phosphate oxygen atom of the pyrimidine nucleotides (cmp,ump,dtmp) were studied at the hartree-fock level theory. we used lanl2dz basis set for mg and 6-31g* basis set for atoms.the basis set superposition error (bsse) begins to converge for used method/basis set. the gauge-invariant atomic orbital (giao) method and the continuous-set-of-gauge-transformation (csgt) procedure were employed to calculate isotropic atomic shielding of the nucleotides using density functional theory at the b3lyp/6-31g** . these calculations yield molecular geometries in good agreement with available experimental data.