Abstract
The total electric field gradient (EFG) tensor V pq is calculated by numerical integration of threedimensional integrals. Each of them is solved a) by integrating over one dimension analytically and b) by integrating over the remaining two dimensions on the basis of a Gauss-type integration rule. The use of 100 abscissas in the twodimensional numerical integration scheme yields satisfactory accuracy which was checked by evaluating overlap integrals; an increase to 400 abscissas does not increase the result drastically. Calculating quadrupole splittings ΔE Q from numerically integrated electric field gradient tensors V pq we observe that depending a) on the amount of covalency and b) on the amount of deviation from octahedral or tetrahedral symmetry, involved in a molecular system, overlap and ligand contributions to V pq play an important role. Especially for the sandwich compound ferrocene, Fe(C5H5)2, we find a significant difference between ΔE num. int.Q which follows from the numerical integration method, and ΔE conventionalQ which is derived from effective charges.
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Reschke, R., Trautwein, A. Numerical integration of overlap and ligand contributions to the electric field gradient. Theoret. Chim. Acta 47, 85–96 (1978). https://doi.org/10.1007/BF00547746
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DOI: https://doi.org/10.1007/BF00547746