Density functional theory using accepted semi‐local exchange‐correlation functionals is generally successful for structural properties. However, for electrical response calculations of extended molecular systems, like e.g. polyacetylene, they make large errors; for the hyperpolarizability the error can be several orders of magnitude. The errors can be traced to qualitative differences between the exchange potentials of semi‐local and exact exchange methods. A recent effort has been successful in using a corrective term based on semi‐local quantities to introduce the missing features directly into the exchange potential (as opposed to modeling the exchange‐correlation energy). The resulting potential reproduces the derivative discontinuity, step structure, and counteracting field slope of exact exchange. It gives the polarizability of hydrogen chains with similar accuracy as exact exchange methods.

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