Foundation 3: What is covered in this review?
For the rest of this tutorial review, we will use research articles
published in the past decade to extract some simple representative
calculation that focus on different undervalued aspects of DFT. We
collected all calculations in the form of a series of experiments in a
laboratory notebook provided in the Supporting Information (SI). We
invite the readers to try all experiments on their own and to compare
their answers with the ones provided as a key. All calculations can be
performed on desktop computers or even on a laptop, and they should take
at maximum just a few hours. Mirroring the structure of this essay, we
collected the experiments into three groups, the first dealing with the
foundations of the theory, where we mainly test the knowledge of the
acronyms used in the computational chemistry community. The second group
deals with the choice of the method (where method refers to the
combination of a functional and a basis set), and the third deals with
the technical issues. The three groups have a total of 12 activities,
plus an additional final self-assessment test/questionnaire. The
experiments and their take-home messages are summarized in Table
1 .
Given the vastness of the topic, it was necessary for us to make some
choices on the material to either include or exclude. For example, we
have decided to concentrate exclusively on molecular calculations in
gas-phase based on Gaussian basis functions and Kohn–Sham DFT, because
of their importance in chemistry and related fields of molecular
science. We will not consider orbital-free DFT methods,
projector-augmented wave and related methods, and several flavors of
plane-waves and periodic boundary conditions-based KS-DFT calculations,
despite their importance in the solid state and material science
community. For some of those topic, we refer the reader to recent
reviews57–67
Even on the chemical side, we will not discuss some of the important
corollary aspects of molecular calculations, such as solvation models,
calculation of partial atomic charges, use and interpretation of
molecular orbitals, calculations with effective core potentials, as well
as calculations of associated properties (such as prediction of spectra,
polarizabilities, magnetic properties, etc). We left these topics out
because they are not strictly bound to KS-DFT itself, since they equally
apply to most of quantum chemical calculation methods, including
wave-function-theory–based ones. Each of these subjects deserves a
thorough treatment, for which we refer to specific field studies and
reviews, such as Baik et al.68 for solvation models.
Finally, for investigating the state-of-the-art in DFT research
development and application, we refer the readers to the recent reviews
and perspectives.16,19,22,25,26,36,43,69