Zeroth-order regular approximation energies/results

Table 4.13 Distance of C atom to closest Pt atom in the surface (Rpt-c) and binding energy ( b) for CO adsorbed on Pt(l 11) in the on-top position RDVM results versus complete active space self-consistent-field data (CASSCF) (Roszak and Balasubramanian 1995) and GGA results within the zeroth-order regular approximation (ZDRA) (Philipsen et al. 1997). Exp. Ogletree et al. (1986).

A truncation of the expansion (3.5) defines the zero- and first-order regular approximation (ZORA, FORA) (van Lenthe et al. 1993). A particular noteworthy feature of ZORA is that even in the zeroth order there is an efficient relativistic correction for the region close to the nucleus, where the main relativistic effects come from. Excellent agreement of orbital energies and other valence-shell properties with the results from the Dirac equation is obtained in this zero-order approximation, in particular in the scaled ZORA variant (van Lenthe et al. 1994), which takes the renormalization to the transformed large component approximately into account, using... 

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