Corrections for overlapping spheres in the self-consistent field Xα scattered wave method: Part 2. Application to NH 3

Abstract

A modification of the self-consistent field Xα scattered wave (SCF-Xα-SW) method with overlapping spheres was proposed, and the application to H 2O was reported in Part 1. In the present paper, the SCF-Xα-SW method with non-overlapping spheres (MT method), with overlapping spheres but using the MT formulation (OS method), and with overlapping spheres using our corrections (COS method) are applied to the study of ground states of NH 3. In general, trends in the effects on the electronic charge distribution, the total Xα energy and the orbital energies due to the inclusion of the overlapping spheres, with and without the proper corrections, agree with the results for H 2O. Corrections of overlapping spheres are found to be significant when the percentage overlap is equal to or greater than 0.5%. Computation times for the three methods are comparable. Criteria for choosing the radii of the atomic spheres were also investigated. The calculated valence orbital energies of NH 3 with an optimal set of atomic radii are E(3 α 1) = −0.8802 Ry, E (1 e) = −1.1658 Ry and E(2 α 1) = − 2.0159 Ry compared with experimental values of E(3 α 1) = −0.8812 Ry, E(1 e) = −1.1614 Ry and E(2 α 1) = −2.0213 Ry respectively.