diff --git a/Manuscript/eDFT.tex b/Manuscript/eDFT.tex index 4c7f530..0f1ec22 100644 --- a/Manuscript/eDFT.tex +++ b/Manuscript/eDFT.tex @@ -333,7 +333,9 @@ c}\left[n\right]}{\partial w_K} \right| _{n=n_{\opGamma{\bw}}}. \eeq - +%%%%%%%%%%%%%%%% +\subsection{One-electron reduced density matrix formulation} +%%%%%%%%%%%%%%%% For implementation purposes, we will use in the rest of this work (one-electron reduced) density matrices as basic variables, rather than Slater determinants. If we expand the @@ -362,7 +364,9 @@ n_{\bmg^{(K)}}(\br)= %\sum_{\sigma=\alpha,\beta}\sum_{\mu\nu}\AO{\mu}({\br, %\sigma})\AO{\nu}(\br,\sigma){\Gamma}^{(K)}_{\mu\nu}. \eeq +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Manu's derivation %%% +\iffalse%% \blue{ \beq n_{\bmg^{(K)}}(\br)&=&\sum_\sigma\left\langle\hat{\Psi}^\dagger(\br\sigma)\hat{\Psi}(\br\sigma)\right\rangle^{(K)} @@ -378,11 +382,13 @@ p}}c^\sigma_{{\nu p}}\AO{\mu}(\br)\AO{\nu}(\br) p}}c^\sigma_{{\nu p}} \eeq } -%%%% +\fi%%% +%%%% end Manu We can then construct the ensemble density matrix and the ensemble density as follows: \beq -{\bmg}^{{\bw}}=\sum_{K\geq 0}w_K{\bmg}^{(K)} +{\bmg}^{{\bw}}=\sum_{K\geq 0}w_K{\bmg}^{(K)}\equiv +\Gamma_{\mu\nu}^{\bw\sigma}=\sum_{K\geq 0}w_K \Gamma_{\mu\nu}^{(K)\sigma} \eeq and \beq @@ -406,12 +412,43 @@ n({\br})}\left(n_{\bmg^{(I)}}(\br)-n_{\bmg^{\bw}}(\br)\right) c}\left[n\right]}{\partial w_K}\right|_{n=n_{\bmg^{\bw}}} , \eeq -where ${\bm -h}\equiv\left\{\langle\AO{\mu}\vert-\frac{1}{2}\nabla_{\br}^2+v_{\rm -ne}(\br)\vert\AO{\nu}\rangle\right\}_{\mu\nu}$ and ${\bm G}\equiv{\bm J}-{\bm K}$ denote -the Coulomb-exchange -integrals. +where +\beq +{\bm +h}\equiv h_{\mu\nu}= +%\langle\AO{\mu}\vert-\frac{1}{2}\nabla_{\br}^2+v_{\rm +%ne}(\br)\vert\AO{\nu}\rangle +\int d\br\;\AO{\mu}(\br)\left[-\frac{1}{2}\nabla_{\br}^2+v_{\rm +ne}(\br)\right]\AO{\nu}(\br) +\eeq +denote the one-electron integrals matrix. +The individual Hx energy is obtained from the following trace +\beq +\Tr(\bmg^{(K)} \, \bG \, +\bmg^{(L)})=\sum_{\mu\nu\lambda\omega}\sum_{\sigma=\alpha, \beta}\sum_{\tau=\alpha,\beta}G_{\mu\nu\lambda\omega}^{\sigma\tau} +\Gamma_{\mu\nu}^{(K)\sigma}\Gamma_{\lambda\omega}^{(L)\tau} +\nonumber\\ +\eeq +where the two-electron Coulomb-exchange integrals read +\beq +G_{\mu\nu\lambda\omega}^{\sigma\tau}=({\mu}{\nu}\vert{\lambda}{\omega}) +-\delta_{\sigma\tau}(\mu\omega\vert\lambda\nu), +\eeq +with +\beq +(\mu\nu|\la\omega) = \iint \frac{\AO\mu(\br_1) \AO\nu(\br_1) +\AO\la(\br_2) \AO\omega(\br_2)}{\abs{\br_1 - \br_2}} d\br_1 d\br_2 +. +\nonumber\\ +\eeq +Note that, in Sec.~\ref{sec:results}, the theory is applied to (1D) spin +polarized systems in which $\Gamma_{\mu\nu}^{(K)\beta}=0$ and +$G_{\mu\nu\lambda\omega}^{\alpha\alpha}\equiv G_{\mu\nu\lambda\omega}=({\mu}{\nu}\vert{\lambda}{\omega}) +-(\mu\omega\vert\lambda\nu)$. +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%% Hx energy ... %%% Manu's derivation +\iffalse%%%% \blue{ \beq &&\dfrac{1}{2}\sum_{PQRS}\langle PQ\vert\vert @@ -460,9 +497,10 @@ n_{p^\sigma}^{(K)\sigma}n_{q^\sigma}^{(L)\sigma}\right) \Gamma_{\mu\nu}^{(K)\sigma}\Gamma_{\lambda\omega}^{(L)\tau} \eeq } +\fi%%%%%%% %%%% %%%%%%%%%%%%%%%%%%%%% -%\iffalse%%%% Manu's derivation ... +\iffalse%%%% Manu's derivation ... \blue{ \beq n^{\bw}({\br})&=&\sum_{K\geq 0}\sum_{\sigma=\alpha,\beta}{\tt @@ -488,33 +526,8 @@ w}_K \nonumber\\ &=&\sum_{\sigma=\alpha,\beta}\sum_{\mu\nu}\AO{\mu}({\bfx})\AO{\nu}({\bfx}){\Gamma}^{\bw}_{\mu\nu} \eeq -With the notations T2 prefers ... -\beq -n^{\bw}({\br})&=&\sum_{K\geq 0}\sum_{\sigma=\alpha,\beta}{\tt -w}_Kn^{(K)}({\bfx}) -\nonumber\\ -&=& -\sum_{K\geq 0}\sum_{\sigma=\alpha,\beta}{\tt -w}_K\sum_{pq}\varphi_p({\br})\varphi_q({\br})\Gamma_{pq}^{(K)} -\nonumber\\ -&=& -\sum_{\sigma=\alpha,\beta} -\sum_{K\geq 0} -{\tt -w}_K\sum_{p\in (K)}\varphi^2_p({\bfx}) -\nonumber\\ -&=& -\sum_{\sigma=\alpha,\beta} -\sum_{K\geq 0} -{\tt -w}_K -\sum_{\mu\nu} -\sum_{p\in (K)}c_{\mu p}c_{\nu p}\AO{\mu}({\bfx})\AO{\nu}({\bfx}) -\nonumber\\ -&=&\sum_{\sigma=\alpha,\beta}\sum_{\mu\nu}\AO{\mu}({\bfx})\AO{\nu}({\bfx}){\Gamma}^{\bw}_{\mu\nu} -\eeq } -%\fi%%%%%%%% end +\fi%%%%%%%% end %%%%%%%%%%%%%%% %\subsection{Hybrid GOK-DFT} %%%%%%%%%%%%%%% @@ -544,6 +557,29 @@ c}\left[n_{\bm\gamma^{\bw}}\right] \Big\}. \nonumber\\ \eeq +The minimizing ensemble density matrix fulfills the following +stationarity condition +\beq +{\bm F}^{\bw\sigma}{\bm \Gamma}^{\bw\sigma}{\bm S}={\bm S}{\bm +\Gamma}^{\bw\sigma}{\bm F}^{\bw\sigma}, +\eeq +where ${\bm S}\equiv S_{\mu\nu}=\braket{\AO{\mu}}{\AO{\nu}}$ is the +metric and the ensemble Fock-like matrix reads +\beq +F_{\mu\nu}^{\bw\sigma}=h^\bw_{\mu\nu}+\sum_{\lambda\omega}\sum_{\tau=\alpha,\beta} +G_{\mu\nu\lambda\omega}^{\sigma\tau}\Gamma^{\bw\tau}_{\lambda\omega} +\eeq +with +\beq +h^\bw_{\mu\nu}=h_{\mu\nu}+ +%\left\langle\AO{\mu}\middle\vert\dfrac{\delta E^\bw_{\rm +%c}[n_{\bmg^\bw}]}{\delta n(\br)}\middle\vert\AO{\nu}\right\rangle +\int d\br\;\AO{\mu}(\br)\dfrac{\delta E^\bw_{\rm +c}[n_{\bmg^\bw}]}{\delta n(\br)}\AO{\nu}(\br). +\eeq + +%%%%%%%%%%%%%%% +\iffalse%%%%%% % Manu's derivation %%%% \color{blue} I am teaching myself ...\\ @@ -659,13 +695,11 @@ F_{\mu\nu}^\sigma=h_{\mu\nu}+\sum_{\lambda\omega}\sum_\tau G_{\mu\nu\lambda\omega}^{\sigma\tau}\Gamma^{\bw\tau}_{\lambda\omega} \eeq and -\beq -G_{\mu\nu\lambda\omega}^{\sigma\tau}=({\mu}{\nu}\vert{\lambda}{\omega}) --\delta_{\sigma\tau}(\mu\omega\vert\lambda\nu) -\eeq \color{black} \\ -%%%%% +\fi%%%%%%%%%%% +%%%%% end Manu +%%%%%%%%%%%%%%%%%%%% Note that this approximation, where the ensemble density matrix is optimized from a non-local exchange potential [rather than a local one, as expected from Eq.~(\ref{eq:var_ener_gokdft})] is applicable to real @@ -994,7 +1028,7 @@ For TDLDA, the validity of the Tamm-Dancoff approximation (TDA) has been also te Concerning the eKS calculations, two sets of weight have been tested: the zero-weight limit where $\bw = (0,0)$ and the equi-ensemble (or state-averaged) limit where $\bw = (1/3,1/3)$. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -\section{Results and discussion} +\section{Results and discussion}\label{sec:results} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% In Fig.~\ref{fig:EvsL}, we report the error (in \%) in excitation energies (compared to FCI) for various methods and box sizes in the case of 5-boxium (i.e., $\Nel = 5$). Similar graphs are obtained for the other $\Nel$ values and they can be found --- alongside the numerical data associated with each method --- in the {\SI}.