Density functional theory bond breaking

Here S(R) is the overlap integral / abdr and a and b are taken as normalized to unity. While S is a smooth function of Ry the CF calculations show that a derivative discontinuity exists in A(R) at R = 1.6RequmMum- Simple approximations in density functional theory do not reproduce this type of bond-breaking behaviour. 

In this review we focus on applications of the LFDFT method to complexes of 3d metals and compare these with both spectral data from well documented sources [1, 2] and other theoretical methods, such as the spectroscopically oriented Cl (SORCI) method [7] and time-dependent density-functional theory (TDDFT) [8-17]. In particular we intend to emphasize applications to systems with atypical electronic properties of interest for bio-inorganic chemistry and homogeneous catalysis. These systems include macrocyclic amines of Fe in various oxidation states, which are of interest for enzymatic and catalytic reactivity both for redox and bond-breaking reactions. 

In proteins, cysteines form disulfide bond and exist as cystine units (dimer of cysteine) which is one of the causes of helicity of proteins. Keeping in mind the strong affinity of Au towards sulfur, it is assumed that Au ions bind to cysteine residues of the proteins. When Au ions are uptaken by the protein, disulfide bonds break and protein secondary structure is lost. This process can help the bare clusters to achieve their stability in gas phase. This was explained taking Auss as a model through density functional theory calculations. 

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