Showing papers by "Ernest R. Davidson published in 1991"
TL;DR: Improved estimates of the nonrelativistic stationary nucleus correlation energies of the ground-state atomic ions with three to ten electrons and up to 20 are derived by combining experimental data and improved calculations with relativistic complete-valence-space Hartree-Fock energies.
Abstract: Improved estimates of the nonrelativistic stationary nucleus correlation energies of the ground-state atomic ions with three to ten electrons and Z up to 20 are derived by combining experimental data and improved ab initio calculations. Unlike previous work in this area, we focus on the correlation contribution to individual ionization energies, computed by comparing experimental data with relativistic complete-valence-space Hartree-Fock energies.
317 citations
TL;DR: In this paper, two new forms of perturbation theory are presented that are applicable to open shell systems, based entirely on the restricted open shell Hartree-Fock formalism and can be used on the lowest energy of a given symmetry at that geometry.
129 citations
75 citations
TL;DR: Al 2 (O-t-Bu) 6 as mentioned in this paper is a pseudotetrahedral molecule with O−O bond lengths that are ca. 0.16 A shorter than the sum of their atomic radii.
Abstract: The reaction between Al 2 (NMe 2 ) 6 and excess t-BuOH yields Al 2 (O-t-Bu) 6 , which crystallizes in the space group P1 with a =9.946 A, b=9.755 A, c=16.332 A, α=88.89°, β=73.81°, γ=88.89°, and Z=2. The molecule is pseudotetrahedral about each Al center and exhibits terminal Al−O bond lengths that are ca. 0.16 A shorter than the sum of their atomic radii
63 citations
TL;DR: In this paper, the ground vibronic state of CH+4 was analyzed using diabatic basis sets and approximations for Jahn-Teller vibronic problems using the relatively simple E⊗e case.
Abstract: In attempting to understand the ground vibronic state of CH+4, a new formalism was developed for discussing molecular symmetry groups. Various diabatic basis sets and approximations for Jahn–Teller vibronic problems were examined, using the relatively simple E⊗e case. Finally, the symmetries and form of the ground vibronic states of CH+4 were produced.
24 citations
22 citations
13 citations
TL;DR: In this paper, the authors use the term ESR to refer to both electron spin resonance and electron paramagnetic resonance (EPR) spectroscopy, and distinguish them through the use of the label EPR.
Abstract: Atoms and molecules which contain unpaired electrons possess magnetic moments due to the electron’s intrinsic spin and, in cases where the total spin S ≠ 0, to the electron’s orbital angular momentum. Experimental techniques which measure the interaction of the intrinsic spin with an external magnetic field fall into the category of “electron spin resonance” (ESR) spectroscopy. Techniques which deal with orbital angular momemtum are often differentiated through the use of the label “electron paramagnetic resonance” (EPR) spectroscopy. In this article we shall use the term ESR to refer to both.
6 citations