ENERGIES AND STRUCTURES OF ISOMERS OF CL2O2 CALCULATED BY DENSITY-FUNCTIONAL METHODS

The geometries and the relative energies of three low-lying (ClO)(2) i somers in the ground state have been calculated using density function al theory (DFT) methods. The DFT relative energies using extended basi s sets vary by as much as 4.5 cal/mol, depending upon the functionals employed, but differ by less than 2.5 cal/mol from the available CCSD( T) results with large atomic natural orbital basis sets. DFT calculate d geometries of the isomers are also in reasonable agreement with expe riment. The present study shows that the DFT methods could be used to investigate relative energetics of (ClO)(2) isomers, for which large b asis sets are essential even for modest accuracy. (C) 1998 Elsevier Sc ience B.V.