Propagator matrices as matrices of power's series. II. It's relationship with HF's stability problem and alternative solutions |
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Authors: | C A Gmez P F Provasi G A Aucar |
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Institution: | Physics Department, Northeastern University, Av. Libertad 5500, Corrientes W 3404 AAS, Argentina |
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Abstract: | Some non-singlet quasi-instabilities (QIs) cases that arise in the calculation of NMR-J parameters are analyzed within response theory. The relationship between ‘very close to zero’ eigenvalues of the principal propagator and the rate of convergency for specific coupling pathways is shown by a power series implemented to calculate the principal propagator matrix. A natural criterion for the analysis of the stability problem emerges from that series. This is more general and accurate compared with previous proposals. Its relationship with π-type molecular orbitals is given. We present an alternative scheme to minimize the effects of non-singlet QIs in such a way that the NMR-J parameters become close to the best theoretical calculations for H2CX (X=CH2, NH and O). |
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Keywords: | Quasi-instability Propagator matrix Random phase level of approach NMR-J parameter |
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