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Generalized open shell SCF theory

✍ Scribed by Rosa Caballol; Ramóan Gallifa; Josep M. Riera; Ramóan Carbóa

Publisher
John Wiley and Sons
Year
1974
Tongue
English
Weight
816 KB
Volume
8
Category
Article
ISSN
0020-7608

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✦ Synopsis

Abstract

A generalized form of the coupling operator technique in SCF theory has been developed. In the formalism presented here, the monoconfigurational problem may be treated as a particular case of the multiconfigurational framework. The matrix form of the operators has been analyzed; in the LCAO context a structure has been found which is very adequate for computational purposes.

Some examples are also presented which show the usefulness of the theory, emphasising the CNDO and INDO approximations. Within the application of the method to ab initio calculations, some He and second row atoms states have been studied. The He first excited singlet is also studied, the result of the analysis of such a problem being that the nonorthogonality between the singlet functions of the fundamental and of the first excited states play a primordial role in the efficiency of the method.

In no case have the calculation problems, appearing in the application of the theory, been of a more difficult nature than those normally found in the application of the formalism for closed shells.

📜 SIMILAR VOLUMES

Some remarks about a generalized SCF cou
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✍ Ramón Carbó; Ramón Gallifa; Josep M. Riera 📂 Article 📅 1975 🏛 Elsevier Science 🌐 English ⚖ 741 KB

Li and He atomic systems rue studied from the point of view of a general monoconfigurational Hartrec-Fock coupling operator formalism. As a conscquencc, it is found that Lagrange multiplier hermitean cond/tions shouId be fulfilled in those electronic systems where hcrmiticity is not present by symme

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## Abstract A method is presented for generating open‐shell equivalence‐restricted SCF orbitals in high‐symmetry situations using Roothaan–Hartree–Fock programs which are adapted for lower symmetry.

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## theories a sufficient condition for these wavefunctions to satisfy the Hellmann-Feynman theorem is that the basis set includes the derivative A0 ax&?+ for any basis x,,.-The new force approach is applicable to wider fields including electronic processes in chemical reactions. Test calculations

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✍ G. T. Klimko; M. M. Mestechkin; B. N. Plakhutin; G. M. Zhidomirov; R. A. Evarest 📂 Article 📅 1990 🏛 John Wiley and Sons 🌐 English ⚖ 819 KB

## Abstract Different methods of averaging of energy over the states of electronic configurations γ^__N__^ (__n__~γ~ = 1, 2, 3 and __N__ = 1, 2, …, 2__n__~γ~ − 1) leading to Roothaan' energy expression are considered. The consequent values of vector coupling coefficients (VCC) in energy functionals

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## Abstract The effect of damping factors on convergence to general stationary solutions in many‐shell SCF theory is discussed using a first order perturbation analysis. Their bearing on the maximum overlap criterion is examined and a comparison made with Hartree damping. Examples are drawn from nu