We discuss several measures of the quality of a molecular orbital. Each requires only that the orbital be associated with a well-defined Fock operator and is thus applicable to both Hartree–Fock and density functional orbitals. One of the measures, the g diagnostic, ranges from g = 0 (perfect) to g = p/2 (poor) and is conceptually simple. We illustrate its usefulness by applying it to a number ...

The valence photoelectron spectrum has been measured for molecular KBr. Experimental energies of the main and satellite structures have been ompared with the results of ab initio calculations based on molecular orbital theory including configuration and multiconfiguration interaction pproaches. Comparison between the experimental KBr spectrum and previously reported Kr valence photoelectron spe...

A scheme of a neural device intended for searching direct correlations between structures and properties of organic compounds without preliminary computation of molecular descriptors (that are invariant with respect to renumbering atoms in a molecule) is suggested. The invariance of a property with respect to renumbering atoms in a molecule is ensured by the architecture of the neural device, w...

We derive radial and vertical distributions of H i and H2 gas densities in our Galaxy by using the terminal velocity method. We calculate the molecular fraction (fmol) defined as the ratio of the molecular hydrogen to total hydrogen gas density at galactic longitude l = 33◦ ∼ 64◦ and galactic latitude b = −2◦ ∼ +2◦. The thickness of the molecular dominant region (fmol ≥ 0.8) is approximately co...

The usual building blocks of molecular orbital theory are one-center atomic orbitals. If we instead use two-center orbitals derived from the exact solution for H2 , a simple calculation of the H2 binding energy yields 4.5 eV, with a Hylleraas correlation factor having no adjustable parameters. Variational minimization with respect to a couple of parameters in our trial function then shifts the ...

We present a preliminary version of a software package, CHEM1D, that performs molecular orbital calculations on onedimensional atoms and molecules using the unadorned Coulomb operator 1/|x1 − x2|. We describe methods for computing the necessary oneand two-electron integrals and outline the overall structure of the package. We use CHEM1D to perform calculations on a set of small molecules and sh...

correlations between carcinogenicity and several molecular orbital characteristics were found. All correlations between molecular orbital properties and carcinogenicity were modified by one or more of the following structural factors: (a) the absence of a 4-nitro group, (b) the absence of a 1-oxide group, or (c) the presence of bulky substituents in position 2 or 3 of the quinoline ring. Any of...