Equation‐of‐motion coupled‐cluster study of Jahn–Teller effect in X 2 E CF 3 O • and CF 3 S •

An ab initio study of the molecular structure of CF 3 O and CF 3 S, fluorinated analogues of the methoxy (CH 3 O) and methylthio (CH 3 S) radicals, was performed. The equation‐of‐motion coupled‐cluster method (EOMIP) using a reference Slater determinant based on the CF 3 X − ‐anion ( X = O, S) ground state with basis sets of triple‐ζ quality was applied for numerical geometry optimizations of stationary points on adiabatic Jahn–Teller surfaces of the X 2 E ground electronic state of CF 3 O and CF 3 S. The Jahn–Teller distortions in the sulfur‐centered species (CH 3 S and CF 3 S) are totally quenched by the strong spin–orbit coupling. However, the CH 3 O and CF 3 O radicals are structurally distorted by the Jahn–Teller effect accompanied by a relatively small spin‐orbit coupling. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006