diff --git a/Manuscript/eDFT.tex b/Manuscript/eDFT.tex index 512c7b3..87c483c 100644 --- a/Manuscript/eDFT.tex +++ b/Manuscript/eDFT.tex @@ -480,7 +480,7 @@ where $\bx{}=(\omega,\br{})$ is a composite coordinate gathering spin and spatia } \fi%%%%%%%%%%%%%%%%%%%%% then the density matrix of the -determinant $\Det{(K)}$ can be expressed as follows in the AO basis +determinant $\Det{(K)}$ can be expressed as follows in the AO basis: \beq \bGam{(K)} \equiv \eGam{\mu\nu}{(K)} = \sum_{\SO{p}{} \in (K)} \cMO{\mu p}{} \cMO{\nu p}{}, \eeq @@ -832,11 +832,12 @@ as well as \textit{curvature}:\cite{Alam_2016,Alam_2017} \eeq The ensemble energy is of course expected to vary linearly with the ensemble weights [see Eq.~\eqref{eq:exact_GOK_ens_ener}]. -These errors are essentially removed when evaluating the individual energy -levels on the basis of Eq.~\eqref{eq:exact_ind_ener_rdm}. +\manu{ +The explicit linear weight dependence of the ensemble Hx energy is actually restored when evaluating the individual energy +levels on the basis of Eq.~\eqref{eq:exact_ind_ener_rdm}.} Turning to the density-functional ensemble correlation energy, the -following ensemble local-density \textit{approximation} (eLDA) will be employed +following ensemble local-density approximation (eLDA) will be employed \beq\label{eq:eLDA_corr_fun} \E{c}{\bw}[\n{}{}]\approx \int \n{}{}(\br{}) \e{c}{\bw}(\n{}{}(\br{})) d\br{}, \eeq @@ -844,7 +845,7 @@ where the ensemble correlation energy per particle \beq\label{eq:decomp_ens_correner_per_part} \e{c}{\bw}(\n{}{})=\sum_{K\geq 0}w_K\be{c}{(K)}(\n{}{}) \eeq -is \titou{explicitly} \textit{weight dependent}. +is explicitly \textit{weight dependent}. As shown in Sec.~\ref{sec:eDFA}, the latter can be constructed from a finite uniform electron gas model. %\titou{Manu, I think we should clearly define here what the expression of the ensemble energy with and without GOC. @@ -859,8 +860,10 @@ reads %Manu, would it be useful to add this equation and the corresponding text? %I think it is useful for the discussion later on when we talk about the different contributions to the excitation energies. %This shows clearly that there is a correction due to the correlation functional itself as well as a correction due to the ensemble correlation derivative -Combining Eq.~\eqref{eq:exact_ind_ener_rdm} with Eq.~\eqref{eq:eLDA_corr_fun} leads to our \titou{final expression of the KS-eLDA energy level} -\titou{\beq\label{eq:EI-eLDA} +Combining Eq.~\eqref{eq:exact_ind_ener_rdm} with +Eq.~\eqref{eq:eLDA_corr_fun} leads to our final expression of the +KS-eLDA energy levels +\beq\label{eq:EI-eLDA} \begin{split} \E{{eLDA}}{(I)} = @@ -868,12 +871,12 @@ Combining Eq.~\eqref{eq:exact_ind_ener_rdm} with Eq.~\eqref{eq:eLDA_corr_fun} le + \Xi_\text{c}^{(I)} + \Upsilon_\text{c}^{(I)}, \end{split} -\eeq} +\eeq where \beq\label{eq:ind_HF-like_ener} \E{HF}{(I)}=\Tr[\bGam{(I)} \bh] + \frac{1}{2} \Tr[\bGam{(I)} \bG \bGam{(I)}] \eeq -is the analog for ground and excited states (within an ensemble) of the HF energy, \titou{and +is the analog for ground and excited states (within an ensemble) of the HF energy, and \begin{gather} \begin{split} \Xi_\text{c}^{(I)} @@ -881,24 +884,25 @@ is the analog for ground and excited states (within an ensemble) of the HF energ \\ & + \int \n{\bGam{\bw}}{}(\br{}) \qty[ \n{\bGam{(I)}}{}(\br{}) - \n{\bGam{\bw}}{}(\br{}) ] - \left. \pdv{\e{c}{{\bw}}(\n{}{})}{\n{}{}} \right|_{\n{}{} = \n{\bGam{\bw}}{}(\br{})} d\br{} + \left. \pdv{\e{c}{{\bw}}(\n{}{})}{\n{}{}} \right|_{\n{}{} = +\n{\bGam{\bw}}{}(\br{})} d\br{}, \\ \end{split} \\ \Upsilon_\text{c}^{(I)} = \int \sum_{K>0} \qty(\delta_{IK} - \ew{K} ) \n{\bGam{\bw}}{}(\br{}) \left. \pdv{\e{c}{\bw}(\n{}{})}{\ew{K}} \right|_{\n{}{}=\n{\bGam{\bw}}{}(\br{})} d\br{}. -\end{gather}} +\end{gather} If, for analysis purposes, we Taylor expand the density-functional correlation contributions around the $I$th KS state density -$\n{\bGam{(I)}}{}(\br{})$, the sum of -the \titou{second term} on the right-hand side +$\n{\bGam{(I)}}{}(\br{})$, the +second term on the right-hand side of Eq.~\eqref{eq:EI-eLDA} can be simplified as follows through first order in $\n{\bGam{\bw}}{}(\br{})-\n{\bGam{(I)}}{}(\br{})$: \beq\label{eq:Taylor_exp_ind_corr_ener_eLDA} - \titou{\Xi_\text{c}^{(I)}} + \Xi_\text{c}^{(I)} = \int \e{c}{\bw}(\n{\bGam{(I)}}{}(\br{})) \n{\bGam{(I)}}{}(\br{}) d\br{} + \order{[\n{\bGam{\bw}}{}(\br{})-\n{\bGam{(I)}}{}(\br{})]^2}. \eeq @@ -912,13 +916,13 @@ Let us stress that, to the best of our knowledge, eLDA is the first density-functional approximation that incorporates ensemble weight dependencies explicitly, thus allowing for the description of derivative discontinuities [see Eq.~\eqref{eq:excited_ener_level_gs_lim} and the -comment that follows] {\it via} the \titou{third term} on the right-hand side +comment that follows] {\it via} the third term on the right-hand side of Eq.~\eqref{eq:EI-eLDA}. According to the decomposition of the ensemble correlation energy per particle in Eq. \eqref{eq:decomp_ens_correner_per_part}, the latter can be recast \begin{equation} -\titou{\Upsilon_\text{c}^{(I)}} +\Upsilon_\text{c}^{(I)} %&= %\int \sum_{K>0} \qty(\delta_{IK} - \ew{K} ) \n{\bGam{\bw}}{}(\br{}) %\Big(\be{c}{(K)}(\n{\bGam{\bw}}{}(\br{})) @@ -939,7 +943,7 @@ thus leading to the following Taylor expansion through first order in $\n{\bGam{\bw}}{}(\br{})-\n{\bGam{(I)}}{}(\br{})$: \beq\label{eq:Taylor_exp_DDisc_term} \begin{split} -\titou{\Upsilon_\text{c}^{(I)}} +\Upsilon_\text{c}^{(I)} %& = \int \sum_{K>0} \qty(\delta_{IK} - \ew{K} ) \n{\bGam{\bw}}{}(\br{}) % \left. \pdv{\e{c}{\bw}(\n{}{})}{\ew{K}} \right|_{\n{}{}=\n{\bGam{\bw}}{}(\br{})} d\br{} %\\ @@ -966,11 +970,10 @@ d\br{} \end{split} \eeq As readily seen from Eqs. \eqref{eq:Taylor_exp_ind_corr_ener_eLDA} and \eqref{eq:Taylor_exp_DDisc_term}, the -role of the correlation ensemble derivative \titou{$\Upsilon_\text{c}^{(I)}$} -\trashPFL{[last term on the right-hand side of Eq.~\eqref{eq:EI-eLDA}]} is, through zeroth order, to substitute the expected +role of the correlation ensemble derivative contribution $\Upsilon_\text{c}^{(I)}$ is, through zeroth order, to substitute the expected individual correlation energy per particle for the ensemble one. -Let us finally note that, while the weighted sum of the +Let us finally mention that, while the weighted sum of the individual KS-eLDA energy levels delivers a \textit{ghost-interaction-corrected} (GIC) version of the KS-eLDA ensemble energy, \ie, \beq\label{eq:Ew-eLDA} @@ -983,7 +986,7 @@ the KS-eLDA ensemble energy, \ie, \end{split} \eeq the excitation energies computed from the KS-eLDA individual energy level -expressions in Eq. \eqref{eq:EI-eLDA} simply reads +expressions in Eq. \eqref{eq:EI-eLDA} can be simplified as follows: \beq\label{eq:Om-eLDA} \begin{split} \Ex{eLDA}{(I)}