Basis set effects on the geometry of C96H24

Abstract

C96H24 has D6h symmetry using the 4-31G, 6-31G, cc-pVDZ, or cc-pVTZ basis sets, but has lower symmetry if the 6-31G∗∗ or 6-311G∗∗ basis sets are used. Changing the carbon 3d exponent in the 6-31G∗∗ basis set can restore the D6h symmetry, but raises the total energy. The question of geometry vs basis set is discussed.