Ab initio quantum chemical calculations of the divinylacetylene molecule wi
th different mutual orientations of vinyl groups are carried out using the
6-31G*/MP2 basis set. The torsional potential is approximated by a Fourier
series. It is shown that the second term of the series dominates. The entha
lpies of the cis- and trans-isomers are nearly equal; the maximum correspon
ds to the gosh-orientation (180.4 cm(-1) with respect to the cis-form). The
vibrational spectra of the compounds with cis-, gosh-, and trans-orientati
ons of vinyl groups are analyzed based on the ab initio calculations. It is
concluded that the experimental data available in the literature agree wit
h the hypothesis that divinylacetylene exists as cis- and trans-isomers.