add figure

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Pierre-Francois Loos 2023-02-08 21:42:37 +01:00
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@ -516,14 +516,25 @@ The second-order renormalized quasiparticle equation is given by
% \qty[ \widetilde{\bF}(s) + \widetilde{\bSig}(\omega; s) ] \bX = \omega \bX,
\qty[ \widetilde{\bF}(s) + \widetilde{\bSig}(\omega = \epsilon_p; s) ] \psi_p(\bx) = \epsilon_p \psi_p(\bx),
\end{equation}
with
\begin{subequations}
\begin{align}
\widetilde{\bF}(s) &= \bF^{(0)}+\bF^{(2)}(s),\\
with a regularized Fock matrix of the form
\begin{equation}
\widetilde{\bF}(s) = \bF^{(0)}+\bF^{(2)}(s),
\end{equation}
and a regularized dynamical self-energy
\begin{equation}
\label{eq:srg_sigma}
\widetilde{\bSig}(\omega; s) &= \bV^{(1)}(s) \left(\omega \bI - \bC^{(0)}\right)^{-1} (\bV^{(1)}(s))^{\dagger}.
\end{align}
\end{subequations}
\widetilde{\bSig}(\omega; s) = \bV^{(1)}(s) \left(\omega \bI - \bC^{(0)}\right)^{-1} (\bV^{(1)}(s))^{\dagger},
\end{equation}
with elements
\begin{equation}
\label{eq:SRG-GW_selfenergy}
\begin{split}
\widetilde{\bSig}_{pq}(\omega; s)
&= \sum_{i\nu} \frac{W_{p,i\nu} W_{q,i\nu}}{\omega - \epsilon_i + \Omega_{\nu} - \ii \eta} e^{-(\Delta_{pi\nu}^2 + \Delta_{qi\nu}^2) s} \\
&+ \sum_{a\nu} \frac{W_{p,a\nu}W_{q,a\nu}}{\omega - \epsilon_a - \Omega_{\nu} + \ii \eta}e^{-(\Delta_{pa\nu}^2 + \Delta_{qa\nu}^2) s}.
\end{split}
\end{equation}
As can be readily seen above, $\bF^{(2)}$ is the only second-order block of the effective Hamiltonian contributing to the second-order SRG quasiparticle equation.
Collecting every second-order term in the flow equation and performing the block matrix products results in the following differential equation
\begin{multline}
@ -547,19 +558,20 @@ For $s\to\infty$, it tends towards the following static limit
\end{equation}
while the dynamic part of the self-energy [see Eq.~\eqref{eq:srg_sigma}] tends to zero, \ie,
\begin{equation}
\lim_{s\to\infty} \widetilde{\bSig}(\omega; s) = 0.
\end{equation}
with
\begin{equation}
\label{eq:SRG-GW_selfenergy}
\begin{split}
\widetilde{\bSig}_{pq}(\omega; s)
&= \sum_{i\nu} \frac{W_{p,i\nu} W_{q,i\nu}}{\omega - \epsilon_i + \Omega_{\nu} - \ii \eta} e^{-(\Delta_{pi\nu}^2 + \Delta_{qi\nu}^2) s} \\
&+ \sum_{a\nu} \frac{W_{p,a\nu}W_{q,a\nu}}{\omega - \epsilon_a - \Omega_{\nu} + \ii \eta}e^{-(\Delta_{pa\nu}^2 + \Delta_{qa\nu}^2) s}.
\end{split}
\lim_{s\to\infty} \widetilde{\bSig}(\omega; s) = \bO.
\end{equation}
Therefore, the SRG flow continuously transforms the dynamical self-energy $\widetilde{\bSig}(\omega; s)$ into a static correction $\widetilde{\bF}^{(2)}(s)$.
This transformation is done gradually starting from the states that have the largest denominators in Eq.~\eqref{eq:static_F2}.
As illustrated in Fig.~\ref{fig:flow}, this transformation is done gradually starting from the states that have the largest denominators in Eq.~\eqref{eq:static_F2}.
%%% FIG 1 %%%
\begin{figure}
\centering
\includegraphics[width=\linewidth]{flow}
\caption{
Evolution of the quasiparticle equation as a function of the flow parameter $s$ in the case of the dynamic SRG-$GW$ flow (magenta) and the static SRG-qs$GW$ flow (cyan).
\label{fig:flow}}
\end{figure}
%%% %%% %%% %%%
%///////////////////////////%
\subsection{Alternative form of the static self-energy}

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