The moleonlar orbital energies and compositions of (Cp₂ZrX₂ (Cp=oyolopentadienyl group; X=F,Cl,I) by the semi-empirioal EHMO method and the electronio transitions of these oomplezes in the visible-UV region have been oalculated.These oaloulations were oheoked with a visible-UY absorption measurement of Cp₂ZrCl₂.The results are as follows.1.The energy level diagrams of all three oomplezes are very similar in character.All the HOMO's are 10b₂ orbitals,and all the LUMO's are 13_α1 orbitals.HOMO's and LUMO's differ in their energy by an amount of 1.51,1.47 and 1.37 eV for F,Cl and I respectively,decreasing in the order F>Cl>I.