Semiempirical molecular orbital studies of phthalocyanines

A semi-empirical MO method, the PEEL method, has been applied in an investigation of the electronic structure and excited states of copper phthalocyanine. The absorption spectrum of CuPc is discussed and assignments are made. New bands ofn- ^*,d-d and CT types are predicted. The calculated values of ESR parameters accord very well with experimental values, indicating that the method gives a correct electronic distribution.

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Zusammenfassung Eine semiempirische MO-Methode, die PEEL-Methode, wurde bei der Untersuchung der Elektronenstruktur und der angeregten Zustände von Kupferphthalocyaninen angewendet. Das Absorptionsspektrum des CuPc wird interpretiert. Neue Banden vomn- ^*-,d-d- und CT-Typ werden vorhergesagt. Die berechneten Werte der ESR-Parameter stimmen gut mit den experimentellen Werten überein, wodurch gezeigt wird, daß die Methode eine korrekte Elektronenverteilung ergibt.

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Résumé Une méthode d'OM semi-empirique, la méthode PEEL, est appliquée à l'étude de la structure électronique et des états excités de la phtalocyanine du cuivre. Le spectre d'absorption de CuPc est discuté et des attributions sont effectuées. De nouvelles bandes de typen- ^*,d-d et CT sont prédites. Les valeurs calculées des paramètres ESR sont en bon accord avec les valeurs expérimentales, indiquant que la méthode donne une distribution électronique correcte.

     

Dynamic correlation for MCSCF wave functions: An effective potential method

A method is suggested which allows the inclusion of dynamic correlation into CASSCF calculations. An effective Coulomb hole potential is added to the Hamiltonian. The potential has a simple form, which allows its implementation into existing LCAO programs using Gaussian integral packages. The parameters appearing in the potential are determined by fitting to empirical valence correlation energies for first row atoms. Calculations of ionization energies and electron affinities show considerable improvement compared to the MCSCF values. Test calculations on three molecules give the following results, H₂ r _e=0.745 (0.741) Å, D _e=4.62 (4.75) eV; N₂ r _e=1.099 (1.098) Å, D _e= 10.42 (9.91) eV; O₂ r _e=1.198 (1.207) Å, D _e=4.73 (5.21) eV. Experimental values within parenthesis. On leave from: Institute of Organic Chemistry, Polish Academy of Sciences, PL-01-224 Warszawa 42, ul. Kasprzaka 44, Poland.     

A theoretical determination of the dissociation energy of the nitric oxide dimer

Summary Multi-reference CI methods have been applied to determine the dissociation energy and structure of thecis-N₂O₂ molecule. The convergence of the theoretical result has been checked with respect to a systematic expansion of the one-electron basis set and the multi-reference CI wave function. The best calculated value, 13.8 kJ/mol, is in agreement with the experimental value, 12.2 kJ/mol. It has been obtained with an extended ANO-type basis set [6s5p3d2f], including the effect of the basis set superposition error (BSSE) in the geometry optimization, and additional effects, such as the electron correlation of core electrons and relativistic corrections, using the average coupled pair functional (ACPF) approach. The optimal geometry computed at this level was found to be:r(NN)=2.284 Å,r(NO)=1.149 Å, and s5p3d2f] basis set, the BSSE was found to be 2 kJ/mol.     

Qualocation for a singularly perturbed boundary value problem

A singularly perturbed one-dimensional two point boundary value problem of reaction–convection–diffusion type is considered. We generate a C⁰$C^0$-collocation-like method by combining Galerkin with an adapted quadrature rule. Using Lobatto quadrature and splines of degree r$r$, we prove on a Shishkin mesh for the qualocation method the same error estimate as for the Galerkin technique. The result is also important for the practical realization of finite element methods on Shishkin meshes using quadrature formulas. We report the results of numerical experiments that support the theoretical findings.     

Primal-dual target-following algorithms for linear programming

In this paper, we propose a method for linear programming with the property that, starting from an initial non-central point, it generates iterates that simultaneously get closer to optimality and closer to centrality. The iterates follow paths that in the limit are tangential to the central path. Together with the convergence analysis, we provide a general framework which enables us to analyze various primal-dual algorithms in the literature in a short and uniform way.This work was completed with the support of a research grant from SHELL. The first author is supported by the Dutch Organization for Scientific Research (NWO), Grant No. 611-304-028. The third author is on leave from the Eötvös University, Budapest, and partially supported by OTKA No. 2116. The fourth author is supported by the Swiss National Foundation for Scientific Research, Grant No. 12-34002.92.     

ChemInform Abstract: Matrix Infrared Spectra and Electronic Structure Calculations of the First Actinide Borylene: FB=ThF2.

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