An assessment of a simple hardness kernel approximation for the calculation of the global hardness in a series of Lewis acids and bases

A simplified model of the hardness kernel, η(r→,r→′)≅δ(r→−r→′), has been evaluated for the calculation of the global hardness in a series of Lewis acids and bases using the MP2 method. It is found that this simple model yields the appropriate ordering of the molecules according to their hardness values when compared to experimental available results.