Configuration interaction first derivatives

Kallay, M., Gauss, J., Szalay, P.G. Analytic first derivatives for general coupled-cluster and configuration interaction models. J. Chem. Phys. 2003, 119, 2991-3004. 

In table 2 our result is compared with the UV spectroscopic result of Klein et al. [26], Also shown are the theoretical results of Zhang et al. [2], Plante et al. [27], and Chen et al. [28], The first of these uses perturbation theory, with matrix elements of effective operators derived from the Bethe-Salpeter equation, evaluated with high precision solutions of the non-relativistic Schrodinger equation. This yields a power series in a and In a. The calculations of Zhang et al. include terms up to O(o5 hi a) but omit terms of 0(ary) a.u. The calculations of Plante et al. use an all orders relativistic perturbation theory method, while those of Chen et al. use relativistic configuration interaction theory. These both obtain all structure terms, up to (Za)4 a.u., and use explicit QED corrections from Drake [29],... 

T. J. Lee, W. D. Allen, and H. F. Schaefer, III, J. Chem. Phys., 87, 7063 (1987). The Analytic Evaluation of Energy First Derivatives for Two-Configuration Self-Consistent Field Configuration Interaction Wavefunctions. Applications to Ozone and Ethylene. 

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