Keyword FUKUI

This keyword is used to enable reactivity analysis based on the Fukui function.
Options:

	FALDA		The LDA kernel will be used in the response equation system. Note that this setting will apply to all response calculations in a run.
	FDKERNEL		A finite difference kernel will be used in the response equation system. Note that this setting will apply to all response calculations in a run.

Description:
Upon activation both Fukui functions, electrophilic and nucleophilic, are evaluated. It is assumed that electrons are removed or added to frontier orbitals. Note that the Fukui function is computed analytically using the method reported by Flores-Moreno et al. [260,261]. In case of a degeneracy of the frontier orbitals an average frontier density is considered.