O modelo do potencial simples como criterio para avaliação da qualidade de cargas atomicas

AUTOR(ES)

Roberto Luiz Andrade Haiduke

DATA DE PUBLICAÇÃO

1999

RESUMO

The quality of Mulliken, Bader, CHELPG and GAPT charges as well as dipole moment derivatives obtained from experimentally measured infrared fundamental gas phase intensities is determined using the simple potential model originally proposed by Siegbahn. More than thirty carbon containing molecules with sp3 , sp2 and sp hybridization states were studied. The atomic charges were calculated with 6-311 ++G(3d,3p) wave functions at the ab initio MP2 and density functional B3LYP levels to include eletronic correlation effects. The importance of charge density relaxation on ionization was studied by calculating relaxation energies at the HF/6-311 ++G(3df,3p) level. Analysis of the simple potential model criterion shows that the GAPT charges and mean dipole moment derivatives are capable of discribing the electrostatic potentials in the vicinities of the carbon nuclei more adequately than the other charges. The simple potential model is also used to show that a sum rule relating carbon 1s ionization energies can be expressed in terms of GAPT charges or mean dipole derivatives.

ASSUNTO(S)

ionização raio x

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