diff --git a/Manuscript/eDFT.tex b/Manuscript/eDFT.tex index 87c978f..510c2fe 100644 --- a/Manuscript/eDFT.tex +++ b/Manuscript/eDFT.tex @@ -298,7 +298,7 @@ HF}\left[\bmg\right]$. This type of errors is specific to ensembles which explains why, in constrast to ground-state DFT [see Eq.~(\ref{eq:generalized_KS-DFT_decomp})], a complementary ensemble Hx energy is needed to recover a ghost-interaction-free energy: -\beq +\beq\label{eq:exact_GIC} \overline{E}^{{\bw}}_{\rm Hx}[n]&=& {\rm @@ -361,7 +361,7 @@ Tr}\left[{\bmg}^{{\bw}}{\bm h}\right]+W_{\rm HF}\left[{\bmg}^{\bw}\right] + \overline{E}^{{\bw}}_{\rm -Hxc}\left[n^{{\bw}}\right] +Hxc}\left[n_{\bmg^{\bw}}\right] %+E^{{\bw}}_{\rm c}\left[n_{\hat{\Gamma}^{{\bw}}}\right] \Big\} \Bigg\} @@ -376,12 +376,14 @@ Tr}\left[{\bmg}^{{\bw}}{\bm h}\right]+W_{\rm HF}\left[{\bmg}^{\bw}\right] + \overline{E}^{{\bw}}_{\rm -Hxc}\left[n^{{\bw}}\right] +Hxc}\left[n_{\bmg^{\bw}}\right] %+E^{{\bw}}_{\rm c}\left[n_{\hat{\Gamma}^{{\bw}}}\right] \Big\} , \eeq -where $n^{\bw}$ is the density obtained from the density matrix +where $n_{\bmg^{\bw}}$ +\manu{I am in favor of using $n_{{\bmg}^{{\bw}}}$ rather than $n_{\bmg^{\bw}}$, +for clarity} is the density obtained from the density matrix ${\bmg}^{\bw}$ and ${\bm h}={\bm t}+{\bm v}_{\rm ext}$ is the total one-electron Hamiltonian matrix representation. When the minimum is reached, the ensemble energy and its derivatives can be used to extract individual @@ -400,11 +402,11 @@ Tr}\left[\left({\bmg}^{(K)}-{\bmg}^{(0)}\right){\bm h}\right] \nonumber\\ &&+ \int d\br\,\dfrac{\delta \overline{E}^{{\bw}}_{\rm -Hxc}\left[n^{{\bw}}\right]}{\delta +Hxc}\left[n_{\bmg^{\bw}}\right]}{\delta n({\br})}\left(n^{(K)}(\br)-n^{(0)}(\br)\right) \nonumber\\ &&+\left. \dfrac{\partial \overline{E}^{{\bw}}_{\rm -Hxc}\left[n\right]}{\partial w_K}\right|_{n=n^{{\bw}}}, +Hxc}\left[n\right]}{\partial w_K}\right|_{n=n_{\bmg^{\bw}}}, \eeq we finally obtain from Eqs.~(\ref{eq:var_princ_Gamma_ens}) and (\ref{eq:indiv_ener_from_ens}) the following in-principle-exact expressions for the energy levels within the ensemble: @@ -415,14 +417,14 @@ Tr}\left[{\bmg}^{(I)}{\bm h}\right]+ \Tr\left[\left(\bmg^{(I)}-\dfrac{1}{2}\bmg^{\bw}\right) \, \bG \, \bmg^{\bw}\right] \nonumber\\ &&+\overline{E}^{{\bw}}_{\rm -Hxc}\left[n^{{\bw}}\right] +Hxc}\left[n_{\bmg^{\bw}}\right] +\int d\br\,\dfrac{\delta \overline{E}^{{\bw}}_{\rm -Hxc}\left[n^{{\bw}}\right]}{\delta -n({\br})}\left(n^{(I)}(\br)-n^{\bw}(\br)\right) +Hxc}\left[n_{\bmg^{\bw}}\right]}{\delta +n({\br})}\left(n^{(I)}(\br)-n_{\bmg^{\bw}}(\br)\right) \nonumber\\ && +\sum_{K>0}\left(\delta_{IK}-w_K\right)\left. \dfrac{\partial \overline{E}^{{\bw}}_{\rm -Hxc}\left[n\right]}{\partial w_K}\right|_{n=n^{{\bw}}}. +Hxc}\left[n\right]}{\partial w_K}\right|_{n=n_{\bmg^{\bw}}}. \eeq %+\Tr(\bmg^{(I)} \, \bG \, \bmg^{\bw}) %-\dfrac{1}{2}\Tr(\bmg^{\bw} \, \bG \, \bmg^{\bw})+... @@ -430,7 +432,7 @@ Hxc}\left[n\right]}{\partial w_K}\right|_{n=n^{{\bw}}}. Note that \beq \overline{E}^{{\bw}}_{\rm -Hx}\left[n^{{\bw}}\right]= +Hx}\left[n_{\bmg^{\bw}}\right]= \frac{1}{2} \sum_{L\geq0}w_L \Tr(\bmg^{(L)} \, \bG \, \bmg^{(L)}) -\frac{1}{2}\Tr(\bmg^{\bw} \, \bG \, \bmg^{\bw}) \nonumber\\ @@ -438,7 +440,7 @@ Hx}\left[n^{{\bw}}\right]= and \beq \left.\dfrac{\partial \overline{E}^{{\bw}}_{\rm -Hx}[n]}{\partial w_K}\right|_{n=n^{\bw}}&=& +Hx}[n]}{\partial w_K}\right|_{n=n_{\bmg^{\bw}}}&=& \frac{1}{2} \Tr(\bmg^{(K)} \, \bG \, \bmg^{(K)})-\frac{1}{2} \Tr(\bmg^{(0)} \, \bG \, \bmg^{(0)}) \nonumber\\ @@ -448,12 +450,12 @@ Hx}[n]}{\partial w_K}\right|_{n=n^{\bw}}&=& thus leading to \beq &&\overline{E}^{{\bw}}_{\rm -Hx}\left[n^{{\bw}}\right]+\sum_{K>0}\left(\delta_{IK}-w_K\right)\left. \dfrac{\partial \overline{E}^{{\bw}}_{\rm -Hx}\left[n\right]}{\partial w_K}\right|_{n=n^{{\bw}}} +Hx}\left[n_{\bmg^{\bw}}\right]+\sum_{K>0}\left(\delta_{IK}-w_K\right)\left. \dfrac{\partial \overline{E}^{{\bw}}_{\rm +Hx}\left[n\right]}{\partial w_K}\right|_{n=n_{\bmg^{\bw}}} \nonumber\\ &&= \overline{E}^{{\bw}}_{\rm -Hx}\left[n^{{\bw}}\right]+\frac{1}{2} \Tr(\bmg^{(I)} \, \bG \, \bmg^{(I)}) +Hx}\left[n_{\bmg^{\bw}}\right]+\frac{1}{2} \Tr(\bmg^{(I)} \, \bG \, \bmg^{(I)}) -\frac{1}{2} \sum_{L\geq0}w_L \Tr(\bmg^{(L)} \, \bG \, \bmg^{(L)}) \nonumber\\ &&-\Tr\left[\left({\bmg}^{(I)}-{\bmg}^{\bw}\right) \, \bG \, \bmg^{\bw}\right] @@ -489,16 +491,16 @@ Tr}\left[{\bmg}^{(I)}{\bm h}\right]+ && +\int d\br\, \overline{\epsilon}^{{\bw}}_{\rm -Hxc}(n^{\bw}(\br))\,n^{(I)}(\br) +Hxc}(n_{\bmg^{\bw}}(\br))\,n^{(I)}(\br) \nonumber\\ && +\int d\br\,\left.\dfrac{\partial \overline{\epsilon}^{{\bw}}_{\rm -Hxc}(n)}{\partial n}\right|_{n=n^{\bw}(\br)}n^{\bw}(\br)\left(n^{(I)}(\br)-n^{\bw}(\br)\right) +Hxc}(n)}{\partial n}\right|_{n=n_{\bmg^{\bw}}(\br)}n_{\bmg^{\bw}}(\br)\left(n^{(I)}(\br)-n_{\bmg^{\bw}}(\br)\right) \nonumber\\ && -+\int d\br\,\sum_{K>0}\left(\delta_{IK}-w_K\right)n^{{\bw}}(\br)\left. ++\int d\br\,\sum_{K>0}\left(\delta_{IK}-w_K\right)n_{\bmg^{\bw}}(\br)\left. \dfrac{\partial \overline{\epsilon}^{{\bw}}_{\rm -Hxc}(n)}{\partial w_K}\right|_{n=n^{{\bw}}(\br)}. +Hxc}(n)}{\partial w_K}\right|_{n=n_{\bmg^{\bw}}(\br)}. \eeq \alert{ or, equivalently, @@ -511,20 +513,72 @@ Tr}\left[{\bmg}^{(I)}{\bm h}\right]+ && +\int d\br\, \dfrac{\delta \overline{E}^{{\bw}}_{\rm -Hxc}\left[n^{\bw}\right]}{\delta +Hxc}\left[n_{\bmg^{\bw}}\right]}{\delta n({\br})}\,n^{(I)}(\br) \nonumber\\ && -\int d\br\,\left.\dfrac{\partial \overline{\epsilon}^{{\bw}}_{\rm -Hxc}(n)}{\partial n}\right|_{n=n^{\bw}(\br)}\Big(n^{\bw}(\br)\Big)^2 +Hxc}(n)}{\partial n}\right|_{n=n_{\bmg^{\bw}}(\br)}\Big(n_{\bmg^{\bw}}(\br)\Big)^2 \nonumber\\ && -+\int d\br\,\sum_{K>0}\left(\delta_{IK}-w_K\right)n^{{\bw}}(\br)\left. ++\int d\br\,\sum_{K>0}\left(\delta_{IK}-w_K\right)n_{\bmg^{\bw}}(\br)\left. \dfrac{\partial \overline{\epsilon}^{{\bw}}_{\rm -Hxc}(n)}{\partial w_K}\right|_{n=n^{{\bw}}(\br)}. +Hxc}(n)}{\partial w_K}\right|_{n=n_{\bmg^{\bw}}(\br)}. \eeq } +\subsection{OEP-like approach} + + +In the exact theory, the minimizing density matrix in +Eq.~(\ref{eq:var_princ_Gamma_ens}) is such that +\beq +{\bmg}^{(K)}[n_{{\bmg}^{{\bw}}}]={\bmg}^{(K)},\hspace{0.2cm}\forall +K\geq0, +\eeq +and therefore +\beq +{\bmg}^{{\bw}}\left[n_{{\bmg}^{{\bw}}}\right]={\bmg}^{{\bw}}. +\eeq +Combining the latter Eqs. with +Eqs. (\ref{eq:exact_GIC}), (\ref{eq:var_princ_Gamma_ens}) leads to +the final ensemble energy expression +\beq +E^{{\bw}}={\rm +Tr}\left[{\bmg}^{{\bw}}{\bm h}\right]+\frac{1}{2} \sum_{L\geq0}w_L +\Tr(\bmg^{(L)} \, \bG \, \bmg^{(L)}) ++\overline{E}^{{\bw}}_{\rm +c}\left[n_{\bmg^{\bw}}\right]. +\nonumber\\ +\eeq + +Note that +\beq +E^{{\bw}}&\neq& \underset{\left\{{\bmg}^{(L)}\right\}_{L\geq 0}}{\rm min}\Big\{ +{\rm +Tr}\left[{\bmg}^{{\bw}}{\bm h}\right]+\frac{1}{2} \sum_{L\geq0}w_L +\Tr(\bmg^{(L)} \, \bG \, \bmg^{(L)}) +\nonumber\\ +&&+\overline{E}^{{\bw}}_{\rm +c}\left[n_{\bmg^{\bw}}\right] +\Bigg\} +\eeq + +\beq +\dfrac{\partial E^{{\bw}}}{\partial w_K}&=& +{\rm +Tr}\left[\left({\bmg}^{(K)}-{\bmg}^{(0)}\right){\bm h}\right] ++\frac{1}{2}\Tr(\bmg^{(K)} \, \bG \, \bmg^{(K)}) +\nonumber\\ +&&-\frac{1}{2}\Tr(\bmg^{(0)} \, \bG \, \bmg^{(0)}) ++\sum_{L\geq0}w_L{\rm +Tr}\left[\dfrac{\partial\bmg^{(L)}}{\partial w_K}{\bm h}\right] +\nonumber\\ +&& ++\sum_{L\geq0}w_L +\Tr(\bmg^{(L)} \, \bG \, \dfrac{\partial\bmg^{(L)}}{\partial w_K}) +\eeq + %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \subsection{KS-eDFT for excited states} \label{sec:KS-eDFT}