COMPARISON OF CONVENTIONAL AB-INITIO AND DENSITY-FUNCTIONAL METHODS FOR THE AR-HF INTERACTION POTENTIAL

The geometry and interatomic potential for the ground state of Ar-H-F was determined by HF, MP2, MP4, QCISD and density functional theory (D FT) methods using 6-311G* basis set. It was found that there is no ag reement between conventional ab initio and DFf methods. Of the two pos sible conformers investigated in this study, Ar-H-F complex is found t o be more stable than the Ar-F-H complex. The present study indicates that the calculated binding energy and geometrical parameters depend o n the choice of various density functionals used in the DFT calculatio n. The results indicate that the 6-311G* basis set is not sufficient to reproduce the experimental binding energy and geometry. Addition of diffuse and polarizable functions in the basis set may enhance the qu ality of prediction. (C) 1998 Elsevier Science B.V.