# name
A simple, clear and pedagogical way of introducing Density Functional Theory

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This article was written as a basis for a talk given in 2016 in the IQTCUB. In 2021 it was submitted for publication
in The Journal of Chemical Education. The Editor-in-Chief Thomas Holme rejected it with arguments such as “While
we are interested in articles that provide content and motivations for including such content in the curriculum, we
are also aware that essentially every course in the chemistry curriculum is already overcrowded with content” and
“there are no citations to literature in chemistry education”. In 2023 it has been published, after a minor revision,
under a CC-by Creative Commons license at the digital repository of the Universitat de Barcelona (http://hdl.handle.net/2445/197800).

# metadata.dc.description.abstract[].value
Density functional theory (DFT) plays a crucial role in computational chemistry, but its introduction in the chemistry curricula poses a challenge to lecturers when it comes to laying down its foundation without using a complex mathematical formalism and to establishing its scope and limitations. This article aims at presenting a simple and clear derivation of the theory that shows up its very general character. It is based on the constrained-search approach, that bears a close parallelism with the wave-function variational theorem, a familiar tool in any quantum chemistry introduction. Notwithstanding its simplicity, this approach shows appealing features, such as providing an explicit connection of the ground-state density with the electronic hamiltonian and an expression for the universal functional appearing in the definition of the energy functional. These lead to a more tangible insight into the theory than the original derivation by Hohenberg and Kohn, which only guarantees the existence of that connection and this functional. On the other hand, the approach highlights that the theory may, in principle, treat open and closed shell ground states on an equal footing, without the need to impose any restriction about the state spin. An interesting result is recalled that guarantees that a Kohn-Sham scheme may always be set up, no matter the open or closed shell character of the ground state nor its degree of electron correlation.

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cc by-nc-nd (c) Paniagua, Juan Carlos, 2023

# metadata.dc.source[].value
Documents de treball / Informes (Ciència dels Materials i Química Física)

# metadata.dc.title[].value
A simple, clear and pedagogical way of introducing Density Functional Theory