A general self-consistent-field tight-binding linear-combination-of-atomic-orbitals (LCAO) formalism is given for three-dimensional polymers containing many atoms in the elementary cell with all neighbors interacting, taking overlap explicitly into account. This formalism, which corresponds essentially to formulation by Roothaan closed-shell molecules, has been developed aid of Hermitian complex matrices. The special cases nearest-neighbor approximation and a linear chain are then derived...

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Electron correlation in atoms and molecules can be analyzed terms of coefficients similar to those used probability theory mathematical statistics. Different defined for angular, radial, momentum axial (left-right), equatorial, radial (in-out) molecules. The are closely related certain the so-called natural expansion wave function. Nonvanishing obtained Fermi independent-particle model as well electron proper. Numerical examples show that order -0.05, suggesting is usually small negative,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies in Coördination Chemistry. I. The Effect of Solvents on Some Bis-(N-alkylsalicylaldimine)-nickel(II) ComplexesLuigi Sacconi, Piero Paoletti, and Giuseppe Del ReCite this: J. Am. Chem. Soc. 1957, 79, 15, 4062–4067Publication Date (Print):August 1, 1957Publication History Published online1 May 2002Published inissue 1 August 1957https://pubs.acs.org/doi/10.1021/ja01572a027https://doi.org/10.1021/ja01572a027research-articleACS...

Conceptual and mathematical difficulties arise in the study of transitions between vibronic states belonging to crossing Born-Oppenheimer hypersurfaces with significantly different positions shapes minimum-energy nuclear configurations (Duschinsky effect). This article presents an analytic procedure for evaluation pertinent coupling integrals, adopting a normal coordinate reference system internal motion harmonic approximation. The Duschinsky effect is properly considered. was applied...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies in Coördination Chemistry. VI. The Dielectric Polarization of Some Metal Chelates N-Alkylsalicylaldimines1L. Sacconi, M. Ciampolini, F. Maggio, and G. Del ReCite this: J. Am. Chem. Soc. 1960, 82, 4, 815–818Publication Date (Print):February 1, 1960Publication History Published online1 May 2002Published inissue 1 February 1960https://pubs.acs.org/doi/10.1021/ja01489a014https://doi.org/10.1021/ja01489a014research-articleACS PublicationsRequest...

Abstract The application of the self‐consistent field ( SCF ) local‐impurity formalism to quasi‐one‐dimensional systems is discussed. We describe a general procedure for an accurate numerical determination Green's function matrix elements unperturbed system. An local impurity in model chain with two orbitals per unit cell reported. changes charge‐bond‐order and total density states due are discussed special emphasis on at critical points (van Hove singularities) band edges. approach used...

Abstract The gross occupations of molecular orbitals in charge‐transfer complexes are defined terms a multiconfigurational scheme over nonorthogonal orbitals. Their physical significance is illustrated by reference to Mulliken's atomic populations, which they the analogs: under well specified approximations corresponding net charges provide uniquely set point representing molecule an electric field. Alternatives and limitations use as measures charge transfer (and methods for obtaining them)...

Abstract After a brief discussion of the physical significance choice basis in molecular calculations, nature and definition an atomic‐orbital for use limited calculations is discussed, view possibility replacing, say, ordinary 2 s p Slater orbitals by appropriate hybridized‐promoted atomic orbitals. It indicated that, if must be defined connection with given interpretation scheme behavior molecules, hybridization promotion may necessary. The two kinds conditions one wish to impose on...

G. Berthier and Del Re, J. Chem. Soc., 1965, 3109 DOI: 10.1039/JR9650003109

Abstract An iterative molecular orbital method is applied to lithium-like metal clusters. iteration procedure based on a linear relationship between bond orders and interatomic distances for nearest neighbours allows determination of the equilibrium geometries. One-dimensional chains, two-dimensional squares, rectangular triangular arrays, cubes, parallelepipeds, tetrahedra with increasing numbers centres are examined. Considerable distortions appear respect regular infinite lattices. The...

The problem of interpreting and correlating the properties five-membered 'aromatic' heterocycles can be solved by re-examining experimental data applying a semi-empirical quantum-chemical calculation. important objections (based mainly on u.v. absorption spectra) to idea that compounds are essentially perturbed cis-dienes shown not valid; amount homocyclic conjugation appears increase in order furan < thiophen pyrrole, case requiring special consideration; no does correspond typically...