Principal component analysis of molecular geometries of Cis- and trans-C2H2X2 with X = F or Cl

Abstract

Gráficos de escores de PC1 e PC2 mostram como as geometrias calculadas dependem de características da função de onda molecular dos cis-e trans-difluoro e dicloroetilenos. PC1 e PC2 separam os resultados obtidos com e sem funções de polarização e com e sem a inclusão de correlação eletrônica. A qualidade das geometrias experimentais é analisada projetando-as nos gráficos dos escores. Usando este procedimento, a geometria de Takeo obtida a partir de transições de microondas não se compara com nenhuma dos cálculos ab initio para o cis-C 2 H 2 Cl 2 , ao passo que a geometria de Schäfer obtida por espectroscopia de difração de elétrons está em boa concordância com aquelas de cálculos MP2/cc-pVDZ, MP2/cc-aug-pvDZ and CCD/cc-pVDZ. PC1 and PC2 score graphs show how calculated molecular geometries depend on characteristics of the molecular wave-functions of cis-and trans-difluoro-and dichloroethylene. PC1 and PC2 separate the results obtained with or without polarization functions and with or without the inclusion of electronic correlation. The quality of the experimental geometries are analyzed projecting them on the PC score graphs. Using this procedure, Takeo's geometry obtained from microwave transitions does not compares with any of the ab initio calculations for cis-C 2 H 2 Cl 2 , whereas Schäfer's geometry obtaines from gas electron diffraction spectroscopy is in good agreement with the MP2/cc-pVDZ, MP2/cc-aug-pVDZ and CCD/cc-pVDZ calculations.

A theoretical study of the hydrogen bonding between the vic-, cis- and trans-C2H2F2 isomers and hydrogen fluoride

“…The vic-, cis-and trans-C 2 H 2 F 2 isomers have been the goal of several theoretical studies [8][9][10][11], in particular because these species contain the same kind and number of chemical bonds. Thus, it is expected that the major difference in their structural, electrical and vibrational properties can be attributed to the different 0022-2860/$ -see front matter Ó 2008 Elsevier B.V. All rights reserved.…”