Table 1 Summary of the general COT approach and its declinations.

From: Connector theory for reusing model results to determine materials properties

 

Kohn–Sham

General

1D potential

Band structure

Object of interest

vxc(r; [n])

O(x; [Q])

E(j; ω0, L)

GKK(k, ω; [V])

Model

HEG

t.b. chosen

1D square well

HEG

Object in model

\({v}_{{{{\rm{xc}}}}}^{h}({n}^{h})\)

\({{{{\mathcal{O}}}}}_{x}({{{\mathcal{Q}}}})\)

\({{{{\mathcal{E}}}}}_{j}(L)={\pi }^{2}{j}^{2}/(2{L}^{2})\)

\({{{{\mathcal{G}}}}}_{{{{\bf{k}}}}\omega {{{\bf{K}}}}}({{{\mathcal{V}}}})\)

Connector

\({n}_{{{{\bf{r}}}}}^{c}[n]\)

\({{{{\mathcal{Q}}}}}_{x}^{c}[Q]\)

\({L}_{j{\omega }_{0}L}^{c}=\frac{\pi j}{\sqrt{2E(j;{\omega }_{0},L)}}\)

\({{{{\mathcal{V}}}}}_{{{{\bf{k}}}}\omega {{{\bf{K}}}}}^{c}\)

Approximation

1st order in densitya

t.b. chosen

1st order in curvature

transferability

Appr. real

\({v}_{{{{\rm{xc}}}}}^{h}({n}_{0})+\int d{{{\bf{r}}}}^{\prime} (n({{{\bf{r}}}}^{\prime})-{n}_{0}){f}_{{{{\rm{xc}}}}}(| {{{\bf{r}}}}-{{{\bf{r}}}}^{\prime} | ;{n}_{0})\)

Oapprox(x; [Q])

Eapprox(j; ω0, L)

G(k) ≈ G(k0)

Appr. model

\({v}_{{{{\rm{xc}}}}}^{h}({n}_{0})+({n}^{h}-{n}_{0}){f}_{{{{\rm{xc}}}}}^{h}({n}_{0})\)

\({{{{\mathcal{O}}}}}_{x}^{{{{\rm{approx}}}}}({{{\mathcal{Q}}}})\)

\({{{{\mathcal{E}}}}}_{j}^{{{{\rm{approx}}}}}(\tilde{L})\,\,\,\,\,\)

\({{{{\mathcal{G}}}}}_{{{{\bf{k}}}}}\approx {{{{\mathcal{G}}}}}_{{{{{\bf{k}}}}}_{0}}\)

Appr. connector

\({n}_{{{{\bf{r}}}}}^{c,{{{\rm{approx}}}}}[n]=\frac{1}{{f}_{{{{\rm{xc}}}}}^{h}({n}_{0})}\int d{{{\bf{r}}}}^{\prime} \,n({{{\bf{r}}}}^{\prime}){f}_{{{{\rm{xc}}}}}(| {{{\bf{r}}}}-{{{\bf{r}}}}^{\prime} | ;{n}_{0})\)

\({{{{\mathcal{Q}}}}}_{x}^{c,{{{\rm{approx}}}}}\)

\({L}_{{\omega }_{0}L}^{c,{{{\rm{approx}}}}}\,\,\,\,\,\,\,\,\,\,\)

\({{{{\mathcal{V}}}}}_{{{{\bf{k}}}}\omega {{{\bf{K}}}}}^{c,{{{\rm{approx}}}}}={{{{\mathcal{V}}}}}_{{{{{\bf{k}}}}}_{0}\omega {{{\bf{K}}}}}^{c}\)

Appr. result

\({v}_{{{{\rm{xc}}}}}^{h}({n}_{{{{\bf{r}}}}}^{c,{{{\rm{approx}}}}}[n])\)

\({{{{\mathcal{O}}}}}_{x}({{{{\mathcal{Q}}}}}_{x}^{c,{{{\rm{approx}}}}})\)

\({{{{\mathcal{E}}}}}_{j}({L}_{{\omega }_{0}L}^{c,{{{\rm{approx}}}}})\)

\({{{{\mathcal{G}}}}}_{{{{\bf{k}}}}\omega {{{\bf{K}}}}}({{{{\mathcal{V}}}}}_{{{{\bf{k}}}}\omega {{{\bf{K}}}}}^{c,{{{\rm{approx}}}}})\)

  1. The general COT approach (third column) is compared to its declination for the illustrations discussed in the present paper: the derivation of a particular Kohn–Sham xc potential beyond the LDA (second column), the calculation of energy levels in a box (fourth column), and the calculation of band structures of crystals (last column). Equation numbers refer to the text and are given when adding useful information.
  2. aOr cutoff Coulomb.