ref update

Manuscript/Ec.bib

@@ -1,13 +1,36 @@
 %% This BibTeX bibliography file was created using BibDesk.
 %% http://bibdesk.sourceforge.net/
 
-%% Created for Pierre-Francois Loos at 2021-07-26 18:14:51 +0200 
+%% Created for Pierre-Francois Loos at 2021-07-28 21:47:27 +0200 
 
 
 %% Saved with string encoding Unicode (UTF-8) 
 
 
 
+@misc{Marie_2021b,
+	archiveprefix = {arXiv},
+	author = {Antoine Marie and F{\'a}bris Kossoski and Pierre-Fran{\c c}ois Loos},
+	date-added = {2021-07-28 21:46:38 +0200},
+	date-modified = {2021-07-28 21:46:50 +0200},
+	eprint = {2106.11305},
+	primaryclass = {physics.chem-ph},
+	title = {Variational coupled cluster for ground and excited states},
+	year = {2021}}
+
+@article{Kossoski_2021,
+	author = {Kossoski, F{\'a}bris and Marie, Antoine and Scemama, Anthony and Caffarel, Michel and Loos, Pierre-Fran{\c c}ois},
+	date-added = {2021-07-28 21:45:35 +0200},
+	date-modified = {2021-07-28 21:45:52 +0200},
+	doi = {10.1021/acs.jctc.1c00348},
+	journal = {J. Chem. Theory Comput.},
+	number = {0},
+	pages = {null},
+	title = {Excited States from State-Specific Orbital-Optimized Pair Coupled Cluster},
+	volume = {0},
+	year = {0},
+	Bdsk-Url-1 = {https://doi.org/10.1021/acs.jctc.1c00348}}
+
 @article{Chilkuri_2021,
 	abstract = {Selected configuration interaction (SCI) methods, when complemented with a second-order perturbative correction, provide near full configuration interaction (FCI) quality energies with only a small fraction of the Slater determinants of the FCI space. However, a selection criterion based on determinants alone does not ensure a spin-pure wave function. In other words, such SCI wave functions are not eigenfunctions of the {\^S}2 operator. In many situations (bond breaking, magnetic system, excited state, etc.), having a spin-adapted wave function is essential for a quantitatively correct description of the system. Here, we propose an efficient algorithm which, given an arbitrary determinant space, generates all the missing Slater determinants allowing one to obtain spin-adapted wave functions while avoiding manipulations involving configuration state functions. For example, generating all the possible determinants with 6 spin-up and 6 spin-down electrons in 12 open shells takes 21 CPU cycles per generated Slater determinant. The selection is still done with individual determinants, and one can take advantage of the basis of configuration state functions in the diagonalization of the Hamiltonian to reduce the memory footprint significantly.},
 	author = {Vijay Gopal Chilkuri and Thomas Applencourt and Kevin Gasperich and Pierre-Fran{\c c}ois Loos and Anthony Scemama},
@@ -432,10 +455,10 @@
 	year = {1985},
 	Bdsk-Url-1 = {https://doi.org/10.1016/0009-2614(85)80934-9}}
 
-@article{Marie_2021,
+@article{Marie_2021a,
 	author = {Antoine Marie and Hugh G. A. Burton and Pierre-Fran{\c c}ois Loos},
 	date-added = {2021-06-18 08:52:50 +0200},
-	date-modified = {2021-06-18 08:53:45 +0200},
+	date-modified = {2021-07-28 21:46:52 +0200},
 	doi = {10.1088/1361-648X/abe795},
 	journal = {J. Phys.: Condens. Matter},
 	pages = {283001},

Manuscript/Ec.tex

@@ -137,11 +137,11 @@ Note that, very recently, several groups \cite{Aroeira_2021,Lee_2021,Magoulas_20
 
 A rather different strategy in order to reach the holy grail FCI limit is to resort to M{\o}ller-Plesset (MP) perturbation theory, \cite{Moller_1934}
 whose popularity originates from its black-box nature, size-extensivity, and relatively low computational scaling, making it easily applied to a broad range of molecular systems.
-Again, at least in theory, one can obtain the exact energy of the system by ramping up the degree of the perturbative series. \cite{Marie_2021}
+Again, at least in theory, one can obtain the exact energy of the system by ramping up the degree of the perturbative series. \cite{Marie_2021a}
 The second-order M{\o}ller-Plesset (MP2) method \cite{Moller_1934} [which scales as $\order*{\Norb^{5}}$] has been broadly adopted in quantum chemistry for several decades, and is now included in the increasingly popular double-hybrid functionals \cite{Grimme_2006} alongside exact HF exchange.
 Its higher-order variants [MP3, \cite{Pople_1976}
 MP4, \cite{Krishnan_1980} MP5, \cite{Kucharski_1989} and MP6 \cite{He_1996a,He_1996b} which scale as $\order*{\Norb^{6}}$, $\order*{\Norb^{7}}$, $\order*{\Norb^{8}}$, and $\order*{\Norb^{9}}$ respectively] have been investigated much more scarcely.
-However, it is now widely recognized that the series of MP approximations might show erratic, slowly convergent, or divergent behavior that limits its applicability and systematic improvability. \cite{Laidig_1985,Knowles_1985,Handy_1985,Gill_1986,Laidig_1987,Nobes_1987,Gill_1988,Gill_1988a,Lepetit_1988,Malrieu_2003,Marie_2021}
+However, it is now widely recognized that the series of MP approximations might show erratic, slowly convergent, or divergent behavior that limits its applicability and systematic improvability. \cite{Laidig_1985,Knowles_1985,Handy_1985,Gill_1986,Laidig_1987,Nobes_1987,Gill_1988,Gill_1988a,Lepetit_1988,Malrieu_2003,Marie_2021a}
 Again, MP perturbation theory and CC methods can be coupled.
 The CCSD(T) method, \cite{Raghavachari_1989} where one includes iteratively the single and double excitations and perturbatively (from MP4 and partially MP5) the triple excitations, known as the ``gold-standard'' of quantum chemistry for weakly correlated systems thanks to its excellent accuracy/cost ratio, is probably the most iconic example of such coupling.
 
@@ -684,7 +684,7 @@ As usually observed, CCSD(T) (MAE of \SI{4.5}{\milli\hartree}) provides similar
 
  
 Second, let us look into the series of MP approximations which is known, as mentioned in Sec.~\ref{sec:intro}, to potentially exhibit ``surprising'' behaviors depending on the type of correlation at play.\cite{Laidig_1985,Knowles_1985,Handy_1985,Gill_1986,Laidig_1987,Nobes_1987,Gill_1988,Gill_1988a,Lepetit_1988,Malrieu_2003}
-(See Ref.~\onlinecite{Marie_2021} for a detailed discussion).
+(See Ref.~\onlinecite{Marie_2021a} for a detailed discussion).
 For each system, the MP series decreases monotonically up to MP4 but raises quite significantly when one takes into account the fifth-order correction.
 We note that the MP4 correlation energy is always quite accurate (MAE of \SI{2.1}{\milli\hartree}) and is only a few millihartree higher than the FCI value (except in the case of s-tetrazine where the MP4 number is very slightly below the reference value): MP5 (MAE of \SI{9.4}{\milli\hartree}) is thus systematically worse than MP4 for these weakly-correlated systems.
 Importantly here, one notices that MP4 [which scales as $\order*{N^7}$] is systematically on par with the more expensive $\order*{N^{10}}$ CCSDTQ method which exhibits a slightly smaller MAE of \SI{1.8}{\milli\hartree}.