Showing papers by "Ernest R. Davidson published in 1990"
TL;DR: In this article, the total self-consistent field binding energy of a small ice cluster is estimated as the sum of two and three body interaction terms using the Morokuma method.
Abstract: In this study, the total self‐consistent field binding energy of a small ice cluster is estimated as the sum of two‐ and three‐body interaction terms. The energy of each term is analyzed using the Morokuma method. Counterpoise calculations were performed to estimate the basis set superposition errors. Additional calculations were done to determine the correlation energy contribution to the total binding energy. Results show that the nearest‐neighbor two‐body components contribute most to the total binding energy, but also that the contiguous three‐body terms must be included to reproduce the total binding energy of the system.
159 citations
TL;DR: In this article, the binding energies and momentum distributions of the two valence orbitals of SiH 4 have been measured by electron momentum spectroscopy, and the measured binding energy spectrum is compared with ADC(3) and ADC(4) many-body Green function calculations.
48 citations
29 citations
TL;DR: In this paper, the correlation potential for two electron atomic ions with atomic numbers from 1 to 10 using the charge density reconstructed from a natural orbital expansion of a Kinoshita-like atomic wave function was computed.
Abstract: The correlation potential is computed for two electron atomic ions with atomic numbers from 1 to 10 using the charge density reconstructed from a natural orbital expansion of a Kinoshita-like atomic wave function. Over the wide range of densities involved, the correlation potentials are not even approximately a local function of the density.
22 citations
TL;DR: In this paper, a multireference singles and doubles configuration interaction (SDCI) wave function was used for low-energy nuclear conformations on the ground state potential surface of the propane cation, and the largest isotropic coupling constant was calculated to be 88.6 G, which is in fair agreement with the experimental value of 98 G obtained in an SF6 matrix at 4 K.
Abstract: Proton isotropic hyperfine coupling constants have been calculated for three low-energy nuclear conformations on the ground state potential surface of the propane cation, using a multireference singles and doubles configuration interaction (MR-SDCI) wave function. The lowest point found on the potential surface hadC
2v
symmetry and the electronic wave function at this point had2B2 symmetry. At this point, the largest isotropic coupling constant is calculated to be 88.6 G, which is in fair agreement with the experimental value of 98 G obtained in an SF6 matrix at 4 K. No support is found for a “long-bond” ground state of lower symmetry thanC
2v
. AnotherC
2v
minimum on the ground state potential energy surface was found at which the wave function had2
B
1 symmetry. At this point, two large coupling constants of 198 G and 35 G were calculated. AC
2v
stationary point was also found on the ground state potential surface at which the wave function had2
A
1 symmetry. At this point, couplings of 86 G and 25 G were obtained. None of these agree closely with the other experimental result of couplings at both 100–110 G and 50–52.5 G which was obtained in freon matrices. It is suggested that the latter spectra might correspond to a dynamical average of two distorted2
A' states inC
s symmetry.
17 citations
TL;DR: In this article, a three-step scheme for resolving severely overlapped component spectra from bilinear matrix-formated data is reported, where a positive basis is first formed consisting of the most dissimilar rows and columns of the matrix.
Abstract: A three-step scheme for resolving severely overlapped component spectra from bilinear matrix-formated data is reported. After the number of sample components is determined, a positive basis is first formed consisting of the most dissimilar rows and columns of the matrix. The concentration factor matrix corresponding to this nonnegative, minimally correlated basis will be diagonal if the basis vectors happen to be feasible estimates of the component spectra. In many cases, the nonnegativity and feasibility constrains are not sufficient to produce a unique set of component spectra estimates. Other criteria, such as the degree of overlap of the resolved spectra, may be used
17 citations
16 citations
TL;DR: In this article, the valence orbital momentum distributions of HF have been calculated using extended Gaussian basis sets at the SCF limit and CI levels and with a numerical Hartree-Fock procedure.
12 citations
TL;DR: It is shown that the exact total-energy eigenvalue of the Schrodinger equation is a functional of the Hartree-Fock charge density and the correction to the energies of these models is a universalfunctional of the model charge density.
Abstract: It is shown that the exact total-energy eigenvalue of the Schrodinger equation is a functional of the Hartree-Fock charge density. Furthermore, the exact correlation energy, defined as the correction to the Hartree-Fock energy, is a universal functional of the Hartree-Fock charge density. Similarly, the exact total energy is a functional of the Xα, Hartree-Fock-Slater, or approximate-density-functional charge density. The correction to the energies of these models is again a universal functional of the model charge density
8 citations
TL;DR: In this article, the electron affinities of alkoxy-radicals can be estimated using a correlation with the 1s orbital energy of the oxygen on the associated alkoxy anion.
Abstract: It has been found that the electron affinities of alkoxy-radicals can be estimated using a correlation with the 1s orbital energy of the oxygen on the associated alkoxy-anion, EA=−0.64503 * (1s orbital energy) −351.58. The method assumes that the species of interest accepts the electron into an orbital which is localized on the oxygen.
3 citations