Chemical Hardness and Its Maximum Principle

Chemical hardness is viewed as the instantaneous electronegativity change with charge (Pearson, 1997)  

Nevertheless, being of a quantum nature, chemical hardness inherently contains fluctuations leading to the inequality or variational form of its evolution towards bonding stabilization as such, within the abovemen-tioned double-variational variational formalism the actual maximum hardness principle is advanced (Chattaraj etal., 1991, 1995 Putz, 2008b)  

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