Avaliação do metodo semi-empirico HAM-3 no calculo de propriedades moleculares

AUTOR(ES)

Paolo Roberto Livotto

DATA DE PUBLICAÇÃO

1987

RESUMO

The behavior of the semiempirical HAM/3(Hydrogenic atoms in molecules - version 3) method in calculation of several molecular properties: heats of f ormation, internal rotational barriers, ionization potentials, electron affinities, dipole moments and charge distribuction was studied. The study permits us to know more about the characteristics of the method. Statistical studies of sets of molecules were made for heats of formation and dipole moments and compared with results of MNDO method. Heats of formation computed with HAM/3 are inferior to those of MNDO. HAM/3 has a tendency of overestimation of dipole moments. HAM/3 ionization potentials of cycloalcanes and fluoroethanes showed the quality of the method ln calculation of these properties. Electron affinitles of organic electron aceptors were reasconably evaluated by the HAM/3 method, although the results were less accurate than those obtained for ionization potentials. HAM/3 showed satisfatry capacity in reprodution of substituint effects in electron affinities of derivatives of p-benzoquinone.

ASSUNTO(S)

orbitais moleculares moleculas

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