On the contribution of triply-excited and quadruply-excited configurations to electron correlation energies in closed-shell systems

The contribution made by triply-excited and quadruply-excited configurations to electron correlation energies in closed-shell systems is examined in detail. Many-body perturbation theory is used to calculate the contribution of these configurations to the correlation energies in 25 atoms and molecules. Calculations are performed for the nitrogen, carbon monoxide and carbon monosulphide molecules for a range of nuclear geometries.     

Excited states of HCl

Ab initio CI calculations are presented for potential curves for the valence states of HCl, for the vertical electronic spectrum and for the potential curve for the B ¹Σ⁺ state. The valence ¹Π, ³Π and ³Σ⁺ states are found to be repulsive. Calculated vertical excitation energies are in good agreement with experiment. The B ¹Σ⁺ curve is predicted to have a double minimum.     

A Capital Place for Dining

Abstract

An Introduction to Categorical Data Analysis : Alan Agresti, New York: Wiley, 1996, 312 pp. Reviewed by Carolyn J. Anderson     

Symmetric prismatic tensegrity structures. Part II: Symmetry-adapted formulations

This paper presents analytical formulations for the symmetry-adapted equilibrium, force density and geometrical stiffness matrices for prismatic tensegrity structures with dihedral symmetries. An analytical expression for the infinitesimal mechanisms is also derived.     

Quantum Cohomology and the Periodic Toda Lattice

We describe a relation between the periodic one-dimensional Toda lattice and the quantum cohomology of the periodic flag manifold (an infinite-dimensional K?hler manifold). This generalizes a result of Givental and Kim relating the open Toda lattice and the quantum cohomology of the finite-dimensional flag manifold. We derive a simple and explicit “differential operator formula” for the necessary quantum products, which applies both to the finite-dimensional and to the infinite-dimensional situations. Received: 20 April 1999 / Accepted: 12 April 2000