Ruben Pauncz


Born August 8, 1920 in Szöreg, Hungary.

Emeritus Professor of Chemistry, Technion, Israel Institute of Technology, Haifa, Israel.
WWW: external link

Author of:

Alternant Molecular Orbital Method, W.B. Saunders Co. Philadelphia (1967). Spin Eigenfunctions, Construction and Use, Plenum Press, New York (1979). The Unitary Group in Quantum Chemistry, Elsevier, Amsterdam (1968), (with F.A. Matsen). The Symmetric Group in Quantum Chemistry, CRC Press, Boca Raton FLA (1995). The Construction of Spin Eigenfunctions, An Excercise Book, Kluwer Academic / Plenum Publishers New York (2000).

Important Contributions:

The spectra of linearly condensed aromatic hydrocarbons on the basis of the elliptical rotator model. Analysis of the atoms in molecules method in the case of the hydrogen molecule. Investigation of a two-dimensional homologous series of aromatic compounds. The use of perturbation method for the quantum chemical investigation of systems built up from identical units. Calculation of the inverse of the overlap matrix in cyclic systems. The electronic correlation problem and the alternant molecular orbital method. General energy expression for alternant systems with closed shell structure. Generalization of the method for states with different multiplicities. Many parameter energy expression. Spin degeneracy problem in the AMO method. Theoretical explanation of Hund's rule. Simple algorithm for the construction of genealogical spin eigenfunctions. Serber type spin eigenfunctions by the projection operator method. Branching diagram for elementary particles with arbitrary spin. Branching diagram and Serber-type spin functions, algorithms for their constructions and special properties. Generalized branching diagram. Combinatorial aspects of the Downward-Robb algorithm. The use of the concept of quasispin for alternant conjugated hydrocarbons. Waller-Hartree double determinant. Studies of the Sanibel coefficients. The paired orbital method.