INTERMOLECULAR INTERACTION POTENTIAL ENERGY FOR F2-F2 SYSTEM WERE INVESTIGATED EMPLOYING A SERIES OF CORRELATION-CONSISTENT BASIS SET CC-PVXZ AND AUG-CC-PVXZ (X=D, T) AT THE MFLLER-PLESSET CORRELATION ENERGY CORRECTION, TRUNCATED AT SECOND-ORDER (MP2), THIRD ORDER (MP3) AND QUADRATIC CONFIGURATION INTERACTION CALCULATION, INCLUDING SINGLE AND DOUBLE SUBSTITUTIONS (QCISD) METHODS. IT IS SHOWN THAT THE INTERACTION POTENTIAL ENERGY AND CHARACTERISTICS ARE SENSITIVE TO THE BASIS SET AND ELECTRON CORRELATION. COUNTERPOISE (CP) CORRECTION WAS EMPLOYED IN ALL SUPERMOLECULAR CALCULATION TO ELIMINATE THE BASIS SET SUPERPOSITION ERROR (BSSE).
THE DEEPEST BSSE-CORRECTED POTENTIAL WELL HAS BEEN OBTAINED AT MP2 LEVEL WITH AUG-CC-PVTZ BASIS SET. CHARACTERISTICS OF THE POTENTIAL ENERGY CURVES SUCH AS WELL-DEPTH, POSITION OF POTENTIAL MINIMUM AND HARD- SPHERE COLLISION DIAMETER HAVE BEEN CALCULATED AND COMPARED WITH THE RESULTS OF MP2/6-31G* CALCULATIONS.