diff --git a/Manuscript/SRGGW.tex b/Manuscript/SRGGW.tex index 7b8e17b..73a0f67 100644 --- a/Manuscript/SRGGW.tex +++ b/Manuscript/SRGGW.tex @@ -480,9 +480,10 @@ Collecting every second-order terms in the flow equation and performing the bloc \dv{\bF^{(2)}}{s} = \bF^{(0)}\bV^{(1)}\bV^{(1),\dagger} + \bV^{(1)}\bV^{(1),\dagger}\bF^{(0)} - 2 \bV^{(1)}\bC^{(0)}\bV^{(1),\dagger} . \end{equation} This can be solved by simple integration along with the initial condition $\bF^{(2)}=\bO$ to give -\begin{equation} - F_{pq}^{(2)}(s) = \sum_{r,v} \frac{\Delta_{prv}+ \Delta_{qrv}}{\Delta_{prv}^2 + \Delta_{qrv}^2} W_{p,(r,v)} W^{\dagger}_{(r,v),q}\left(1 - e^{-(\Delta_{prv}^2 + \Delta_{qrv}^2) s}\right). -\end{equation} +\begin{align} + &F_{pq}^{(2)}(s) = \\ + &\sum_{r,v} \frac{\Delta_{prv}+ \Delta_{qrv}}{\Delta_{prv}^2 + \Delta_{qrv}^2} W_{p,(r,v)} W^{\dagger}_{(r,v),q}\left(1 - e^{-(\Delta_{prv}^2 + \Delta_{qrv}^2) s}\right), \notag +\end{align} with $\Delta_{prv} = \epsilon_p - \epsilon_r - \text{sign}(\epsilon_r-\epsilon_F)\Omega_v$. At $s=0$, this second-order correction is null while for $s\to\infty$ it tends towards the following static limit @@ -495,10 +496,11 @@ Therefore, the SRG flow transforms the dynamic part of $\bSig(\omega)$ into a st This transformation is done gradually starting from the states that have the largest denominators in Eq.~\eqref{eq:static_F2}. Interestingly, the static limit, \ie $s\to\infty$ limit, of Eq.~\eqref{eq:GW_renorm} defines an alternative qs$GW$ approximation to the one defined by Eq.~\eqref{eq:sym_qsgw} which matrix elements read as -\begin{equation} - \label{eq:static_F2} - \Sigma_{pq}^{\text{qs}GW}(\eta) = \sum_{r,v} \left( \frac{\Delta_{prv}}{\Delta_{prv}^2 + \eta^2} +\frac{\Delta_{qrv}}{\Delta_{qrv}^2 + \eta^2} \right) W_{p,(r,v)} W^{\dagger}_{(r,v),q}. -\end{equation} +\begin{align} + \label{eq:sym_qsGW} + &\Sigma_{pq}^{\text{qs}GW}(\eta) = \\ + &\frac{1}{2} \sum_{r,v} \left( \frac{\Delta_{prv}}{\Delta_{prv}^2 + \eta^2} +\frac{\Delta_{qrv}}{\Delta_{qrv}^2 + \eta^2} \right) W_{p,(r,v)} W^{\dagger}_{(r,v),q}. \notag +\end{align} Yet, both approximation are closely related as they share the same diagonal terms when $\eta=0$. Also, note that the SRG static approximation is naturally Hermitian as opposed to the symmetrized case where it is enforced by symmetrization. @@ -508,7 +510,8 @@ Indeed, in qs$GW$ calculation using the symmetrized static form, increasing $\et Therefore, we will define the SRG-qs$GW$ static effective Hamiltonian as \begin{align} \label{eq:SRG_qsGW} - \Sigma_{pq}^{\text{SRG}}(s) = \frac{1}{2} \sum_{r,v} \frac{\Delta_{prv}+ \Delta_{qrv}}{\Delta_{prv}^2 + \Delta_{qrv}^2} W_{p,(r,v)} W_{q,(r,v)}\left(1 - e^{-(\Delta_{prv}^2 + \Delta_{qrv}^2) s}\right) + &\Sigma_{pq}^{\text{SRG}}(s) = \\ + &\sum_{r,v} \frac{\Delta_{prv}+ \Delta_{qrv}}{\Delta_{prv}^2 + \Delta_{qrv}^2} W_{p,(r,v)} W_{q,(r,v)}\left(1 - e^{-(\Delta_{prv}^2 + \Delta_{qrv}^2) s}\right) \notag \end{align} which depends on one regularising parameter $s$ analogously to $\eta$ in the usual case. The fact that the $s\to\infty$ static limit does not always converge when used in a qs$GW$ calculation could have been predicted because in this limit even the intruder states have been included in $\tilde{\bF}$. @@ -541,7 +544,6 @@ This means that the cations used an unrestricted HF reference while the neutral \label{sec:results} %=================================================================% - %%%%%%%%%%%%%%%%%%%%%% \section{Conclusion} %%%%%%%%%%%%%%%%%%%%%%