Configuration interaction wavefunction

Bundgen P, Grein F and Thakkar A J 1995 Dipole and quadrupole moments of small molecules. An ab initio study using perturbatively corrected, multi-reference, configuration interaction wavefunctions J. Mol. Struct. (Theochem) 334 7... 

It is possible to use full or limited configuration interaction wavefunctions to construct poles and residues of the electron propagator. However, in practical propagator calculations, generation of this intermediate information is avoided in favor of direct evaluation of electron binding energies and DOs. 

Let us assume that the orbit-generating wavefunction for the nth state is given in the form of a configuration interaction wavefunction (i.e., a linear combination of configuration state functions) ... 

Spin-Orbit Matrix Elements for Internally Contracted Multireference Configuration Interaction Wavefunctions. 

Dynamics calculations of reaction rates by semiempirical molecular orbital theory. POLYRATE for chemical reaction rates of polyatomics. POLYMOL for wavefunctions of polymers. HONDO for ab initio calculations. RIAS for configuration interaction wavefunctions of atoms. FCI for full configuration interaction wavefunctions. MOLSIMIL-88 for molecular similarity based on CNDO-like approximation. JETNET for artificial neural network calculations. More than 1350 other programs most written in FORTRAN for physics and physical chemistry. 

For the configuration interaction wavefunction, however, multiplicative separability is not possible ... 

The molecular spin-orbitals (r) are chosen from a set of orthogonal molecular spin-orbitals i/c(F). Every Slater determinant is built up using different members of the complete set of molecular orbitals. The Slater determinants are referred to as configurations, and a wavefunction such as that in (15) is called a configuration interaction wavefunction. 

The first thing we must do is select a particular orbit. This is done by choosing an initial wavefunction, as the choice of the initial wavefunction determines the orbit. Consider, for example, an arbitrary wavefunction M e cty. This can be a configuration interaction wavefunction or some trial wavefunction incorporating inter-particle coordinates. These wavefunctions must allow for a proper representation of the important physical aspects of the problem at hand. Thus, a configuration interaction wavefunction should contain the minimal set of configurations necessary for the description of electronic correlation. 

The procedure described here for configuration interaction wavefunctions can be extended to explicitly-correlated wavefunctions [73,74]. There is no conceptual difficulty in this extension other than the fact that one must perform all integrations numerically. 

In the non-variational procedure, one sets up an arbitrary orbit-generating wave-function whose form is designed so as to contain the physics" of the problem under consideration. If one were to choose a configuration interaction wavefunction, it... 

Consider again a configuration interaction wavefunction given by Eq. (86). After density optimization within orbit, one has [48,50]... 

Orbital parameters for the Is, 2s and 2p functions appearing in the configuration interaction wavefunction for Be. 

Energy values (in hartrees) for the energy density functional S[p, C°i corresponding to the configuration interaction wavefunctions for Be. 

Considering that the optimal energy for an untransformed function is—14.599936 hartrees (first entry for set C in Table 7), we see that local-scaling transformations have a considerable effect on these configuration interaction wavefunctions. Since the best locally-scaled energy is -14.612495 hartrees (last entry for set C in Table 7), we observe that these transformations improve the energy by -0.012 559 hartrees. 

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. 

Solving the Hartree-Fock equations (5) yields in most cases more than N orbitals and one may accordingly construct improved approximate (so-called Cl, configuration-interaction) wavefunctions... 

P. J. Knowles, P. Pahnieti. Spin-orbit matrix elements for internally contracted multireference configuration interaction wavefunctions. Mol. Phys., 98(21) (2000) 1823-1833. 

M. Dupuis, J. Chem. Phys., 74, 5758 (1981). Energy Derivatives for Configuration Interaction Wavefunctions. 

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