Symmetry-adapted HAM/3 method and its application to some symmetric molecules

Abstract

O método semi-empírico HAM/3, desenvolvido por Lindholm e colaboradores há mais de duas décadas, tem uma deficiência. As energias de excitação calculadas por HAM/3 para estados degenerados são desdobradas. Recentemente foi proposto um método para corrigir esta deficiência. Apresentamos aqui resultados de aplicações deste novo método para algumas moléculas com simetriaO esquema proposto apresenta a degenerescência correta para as moléculas estudadas.The semiempirical HAM/3 method developed by Lindholm and coworkers about two decades ago has been known to have a deficiency that splits energies for the degenerate energy states. We have recently proposed a group-theoretical approach to remedy the internally broken symmetry of the HAM/3 Hamiltonians. In this paper, we present some results of its application to various small molecules with symmetry T d , C 3v , and D 3h . The proposed scheme gives correct degeneracy for these molecules.

Chemometric modeling of core-electron binding energies

“…The presence of several similar or different functional groups and chemical elements besides carbon and hydrogen is a certain enterprise in terms of experimental or theoretical ESCA/CEBE studies. Modern semi-empirical and DFT methodologies for calculation of CEBEs for various chemical elements [23,[28][29][30] enable expansion of such studies to diverse molecules without having measured ESCA binding energies/shifts. Calculated CEBEs/CEBEs shifts have shown to be potential local molecular descriptors in (quantitative) structure-activity relationships (Q)SAR, quantitative structure-property relationships (QSPR), linear free energy relationships (LFER), and related studies [31][32][33].…”