\newcommand{\ie}{\textit{i.e.}} \newcommand{\eg}{\textit{e.g.}} \newcommand{\alert}[1]{\textcolor{red}{#1}} \usepackage[normalem]{ulem} \newcommand{\titou}[1]{\textcolor{red}{#1}} \newcommand{\trashPFL}[1]{\textcolor{red}{\sout{#1}}} \newcommand{\PFL}[1]{\titou{(\underline{\bf PFL}: #1)}} \newcommand{\mc}{\multicolumn} \newcommand{\fnm}{\footnotemark} \newcommand{\fnt}{\footnotetext} \newcommand{\tabc}[1]{\multicolumn{1}{c}{#1}} \newcommand{\SI}{\textcolor{blue}{supplementary material}} \newcommand{\QP}{\textsc{quantum package}} \newcommand{\T}[1]{#1^{\intercal}} % coordinates \newcommand{\br}{\mathbf{r}} \newcommand{\dbr}{d\br} % methods \newcommand{\evGW}{ev$GW$} \newcommand{\qsGW}{qs$GW$} \newcommand{\GOWO}{$G_0W_0$} \newcommand{\Hxc}{\text{Hxc}} \newcommand{\Hx}{\text{Hx}} \newcommand{\xc}{\text{xc}} \newcommand{\Ha}{\text{H}} \newcommand{\co}{\text{c}} \newcommand{\ex}{\text{x}} % \newcommand{\Norb}{N_\text{orb}} \newcommand{\Nocc}{O} \newcommand{\Nvir}{V} \newcommand{\IS}{\lambda} % operators \newcommand{\hH}{\Hat{H}} % methods \newcommand{\KS}{\text{KS}} \newcommand{\HF}{\text{HF}} \newcommand{\RPA}{\text{RPA}} \newcommand{\RPAx}{\text{RPAx}} \newcommand{\TDHF}{\text{TDHF}} \newcommand{\dRPAx}{\text{dRPAx}} \newcommand{\BSE}{\text{BSE}} \newcommand{\TDABSE}{\text{BSE(TDA)}} \newcommand{\dBSE}{\text{dBSE}} \newcommand{\pBSE}{\text{pBSE}} \newcommand{\TDAdBSE}{\text{dBSE(TDA)}} \newcommand{\GW}{GW} \newcommand{\GF}{\text{GF2}} \newcommand{\stat}{\text{stat}} \newcommand{\dyn}{\text{dyn}} \newcommand{\TDA}{\text{TDA}} % energies \newcommand{\Enuc}{E^\text{nuc}} \newcommand{\Ec}{E_\text{c}} \newcommand{\EHF}{E^\text{HF}} \newcommand{\EBSE}{E^\text{BSE}} \newcommand{\EcRPA}{E_\text{c}^\text{RPA}} \newcommand{\EcBSE}{E_\text{c}^\text{BSE}} % orbital energies \newcommand{\e}[1]{\eps_{#1}} \newcommand{\eHF}[1]{\eps^\text{HF}_{#1}} \newcommand{\eKS}[1]{\eps^\text{KS}_{#1}} \newcommand{\eQP}[1]{\eps^\text{QP}_{#1}} \newcommand{\eGW}[1]{\eps^{GW}_{#1}} \newcommand{\eGF}[1]{\eps^{\text{GF2}}_{#1}} \newcommand{\Om}[2]{\Omega_{#1}^{#2}} % Matrix elements \newcommand{\Sig}[1]{\Sigma_{#1}} \newcommand{\SigGW}[1]{\Sigma^{\GW}_{#1}} \newcommand{\SigGF}[1]{\Sigma^{\GF}_{#1}} \newcommand{\MO}[1]{\phi_{#1}} \newcommand{\ERI}[2]{(#1|#2)} \newcommand{\sERI}[2]{[#1|#2]} % excitation energies \newcommand{\OmRPA}[1]{\Omega_{#1}^{\text{RPA}}} \newcommand{\OmRPAx}[1]{\Omega_{#1}^{\text{RPAx}}} \newcommand{\OmBSE}[1]{\Omega_{#1}^{\text{BSE}}} \newcommand{\spinup}{\downarrow} \newcommand{\spindw}{\uparrow} \newcommand{\singlet}{\uparrow\downarrow} \newcommand{\triplet}{\uparrow\uparrow} % Matrices \newcommand{\bO}{\mathbf{0}} \newcommand{\bH}{\mathbf{H}} \newcommand{\bR}{\mathbf{R}} \newcommand{\bS}{\mathbf{S}} \newcommand{\bX}{\mathbf{X}} \newcommand{\bY}{\mathbf{Y}} \newcommand{\bV}{\mathbf{V}} \newcommand{\bI}{\mathbf{1}} \newcommand{\bb}{\mathbf{b}} \newcommand{\bA}{\mathbf{A}} \newcommand{\bB}{\mathbf{B}} \newcommand{\bC}{\mathbf{C}} \newcommand{\bc}{\mathbf{c}} \newcommand{\bx}{\mathbf{x}} % units \newcommand{\IneV}[1]{#1 eV} \newcommand{\InAU}[1]{#1 a.u.} \newcommand{\InAA}[1]{#1 \AA} \newcommand{\kcal}{kcal/mol} % orbitals, gaps, etc \newcommand{\updw}{\uparrow\downarrow} \newcommand{\upup}{\uparrow\uparrow} \newcommand{\eps}{\epsilon} \newcommand{\IP}{I} \newcommand{\EA}{A} \newcommand{\HOMO}{\text{HOMO}} \newcommand{\LUMO}{\text{LUMO}} \newcommand{\Eg}{E_\text{g}} \newcommand{\EgFun}{\Eg^\text{fund}} \newcommand{\EgOpt}{\Eg^\text{opt}} \newcommand{\EB}{E_B} \newcommand{\LCPQ}{Laboratoire de Chimie et Physique Quantiques (UMR 5626), Universit\'e de Toulouse, CNRS, UPS, France}