PCILO CALCULATIONS ON TRUE VANDERWAALS COMPLEXES

The PCILO method was applied to complexes where dispersion energy forms the dominant attractive contribution of the intermolecular interaction energy. With alkane dimers, especially with dimers of higher alkanes (C4H10)2, (C5H12)2, etc., and the ethylene dimer PCILO was successful as to stabilization energy, equilibrium distance, optimal dimer structure, and energy composition. The dispersion energy part is always underestimated, however. With (X2)2 dimers (X = N, F, Cl) PCILO failed, which might be explained by the presence of lone pairs in the subsystems. Copyright © 1979 John Wiley & Sons, Inc.