Utilização de orbitais moleculares localizados no previsão de tensores polares atomicos

AUTOR(ES)

Jose Machado Moita Neto

DATA DE PUBLICAÇÃO

1987

RESUMO

The similarities between the eletronic structure of the C-F bonds, in different molecules, were investigated makin use of the coeficients of the localized molecular orbitais (LMO) corresponding to this bond. The molecular orbital calculations were performed using the CNDO method and localization of the orbitals was based on the method of Edmiston and Ruedenberg. Similarity models were constructed using the coefficients of the localized molecular orbitals and the experimental polar tensor values in the training set molecules, CH3F, CH2F2, CHF3, CF20, trans-C2H2F2, cis -C2H2F2 e 1, 1-C2H2F2. The similarity transference method was applied to a test set (CF4, C2H3F, C2F4, CHFO and CF2S) to predict the polar tensor values of flurine using the coefficients of the LMO s. Also rotationally invariant quantities were used in place of the polar tensor element values. The averages of the absolute and relative errors in the predicted values for all training set molecules, obtained by means of the "leave-one-out" rule is given the following table. For the construction of similarity models the regression method of partial least squares was used. These calculations were carried out using the SIMCA-3B program on a DICON CPM 8 bit 64K byte microcomputer.

ASSUNTO(S)

orbitais moleculares colisões eletron-atomo esterioquimica

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