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@ -2,7 +2,7 @@
%% http://bibdesk.sourceforge.net/
%% Created for Denis Jacquemin at 2019-11-18 18:00:46 +0100
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@ -83,14 +83,65 @@
@string{theo = {J. Mol. Struct. (THEOCHEM)}}
@article{Loo19b,
Author = {Loos, Pierre-Francois and Jacquemin, Denis},
Date-Added = {2019-11-19 19:26:28 +0100},
Date-Modified = {2019-11-19 19:26:28 +0100},
Journal = {ChemPhotoChem},
Pages = {684--696},
Title = {Evaluating 0-0 Energies with Theoretical Tools: a Short Review},
Volume = {3},
Year = {2019}}
@article{Yan04,
Author = {Yanai, T. and Tew, D. P. and Handy, N. C.},
Date-Added = {2019-11-19 19:12:40 +0100},
Date-Modified = {2019-11-19 19:12:40 +0100},
Journal = CPL,
Pages = {51--56},
Title = {A New Hybrid Exchange-Correlation Functional Using the Coulomb-Attenuating Method (CAM-B3LYP)},
Volume = 393,
Year = 2004}
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Author = {Vydrov, O. A. and Scuseria, G. E.},
Date-Added = {2019-11-19 18:56:56 +0100},
Date-Modified = {2019-11-19 18:56:56 +0100},
Journal = JCP,
Pages = {234109},
Title = {Assessment of a long-range corrected hybrid functional},
Volume = 125,
Year = 2006}
@article{Iik01,
Author = {Iikura, H. and Tsuneda, T. and Yanai, T. and Hirao, K.},
Date-Added = {2019-11-19 18:56:25 +0100},
Date-Modified = {2019-11-19 18:56:25 +0100},
Journal = JCP,
Pages = {3540--3544},
Title = {A Long-Range Correction Scheme for Generalized-Gradient-Approximation Exchange Functionals},
Volume = 115,
Year = 2001}
@inbook{Sav96,
Address = {Amsterdam},
Author = {Savin, A.},
Chapter = 9,
Date-Added = {2019-11-19 18:56:17 +0100},
Date-Modified = {2019-11-19 18:56:17 +0100},
Editor = {Seminario, J. M.},
Pages = {327--354},
Publisher = {Elsevier},
Title = {Recent Developments and Applications of Modern Density Functional Theory},
Year = 1996}
@article{Taj18,
Author = {Tajti, Attila and Stanton, John F. and Matthews, Devin A. and Szalay, P{\'e}ter G.},
Date-Added = {2019-11-18 17:57:00 +0100},
Date-Modified = {2019-11-18 17:57:15 +0100},
Date-Modified = {2019-11-19 19:14:51 +0100},
Doi = {10.1021/acs.jctc.8b00681},
Eprint = {https://doi.org/10.1021/acs.jctc.8b00681},
Journal = {J. Chem. Theory Comput.},
Note = {PMID: 30299948},
Number = {11},
Pages = {5859--5869},
Title = {Accuracy of Coupled Cluster Excited State Potential Energy Surfaces},
@ -102,11 +153,10 @@
@article{Taj19,
Author = {Tajti, Attila and Szalay, P{\'e}ter G.},
Date-Added = {2019-11-18 17:56:17 +0100},
Date-Modified = {2019-11-18 17:56:33 +0100},
Date-Modified = {2019-11-19 19:14:55 +0100},
Doi = {10.1021/acs.jctc.9b00676},
Eprint = {https://doi.org/10.1021/acs.jctc.9b00676},
Journal = {J. Chem. Theory Comput.},
Note = {PMID: 31433639},
Number = {10},
Pages = {5523--5531},
Title = {Accuracy of Spin-Component-Scaled CC2 Excitation Energies and Potential Energy Surfaces},
@ -313,9 +363,9 @@
@article{Win13,
Abstract = {In the present study a benchmark set of medium-sized and large aromatic organic molecules with 10--78 atoms is presented. For this test set 0--0 transition energies measured in supersonic jets are compared to those calculated with DFT and the B3LYP functional{,} ADC(2){,} CC2 and the spin-scaled CC2 variants SOS-CC2 and SCS-CC2. Geometries of the ground and excited states have been optimized with these methods in polarized triple zeta basis sets. Zero-point vibrational corrections have been calculated with the same methods and basis sets. In addition the energies have been corrected by single point calculations with a triple zeta basis augmented with diffuse functions{,} aug-cc-pVTZ. The deviations of the theoretical results from experimental electronic origins{,} which have all been measured in the gas phase with high-resolution techniques{,} were evaluated. The accuracy of SOS-CC2 is comparable to that of unscaled CC2{,} whereas ADC(2) has slightly larger errors. The lowest errors were found for SCS-CC2. All correlated wave function methods provide significantly better results than DFT with the B3LYP functional. The effects of the energy corrections from the augmented basis set and the method-consistent calculation of the zero-point vibrational corrections are small. With this benchmark set reliable reference data for 0--0 transition energies for larger organic chromophores are available that can be used to benchmark the accuracy of other quantum chemical methods such as new DFT functionals or semi-empirical methods for excitation energies and structures and thereby augments available benchmark sets augments present benchmark sets which include mainly smaller molec},
Author = {Winter, Nina O. C. and Graf, Nora K. and Leutwyler, Samuel and H{\"a}ttig, Christof},
Author = {Winter, Nina O. C. and Graf, Nora K. and Leutwyler, Samuel and H\"attig, Christof},
Date-Added = {2019-11-18 16:13:25 +0100},
Date-Modified = {2019-11-18 16:13:25 +0100},
Date-Modified = {2019-11-19 19:08:49 +0100},
Doi = {10.1039/C2CP42694C},
Issue = {18},
Journal = {Phys. Chem. Chem. Phys.},
@ -443,11 +493,11 @@
@article{Tro02,
Author = {A. B. Trofimov and G. Stelter and J. Schirmer},
Date-Added = {2019-11-15 20:31:07 +0100},
Date-Modified = {2019-11-15 20:32:01 +0100},
Date-Modified = {2019-11-19 19:27:55 +0100},
Doi = {10.1063/1.1504708},
Journal = {J. Chem. Phys.},
Pages = {6402},
Title = {Electron excitation energies using a consistent third-order propagator approach: Comparison with full configuration interaction and coupled cluster results},
Pages = {6402--6410},
Title = {Electron Excitation Energies Using a Consistent Third-Order Propagator Approach: Comparison with Full Configuration Interaction and Coupled Cluster Results},
Volume = {117},
Year = {2002},
Bdsk-Url-1 = {https://doi.org/10.1063/1.1504708}}
@ -497,14 +547,14 @@
Abstract = {The adiabatic approximation in time-dependent density functional theory (TDDFT) yields reliable excitation spectra with great efficiency in many cases, but fundamentally fails for states of double-excitation character. We discuss how double-excitations are at the root of some of the most challenging problems for \{TDDFT\} today. We then present new results for (i) the calculation of autoionizing resonances in the helium atom, (ii) understanding the nature of the double excitations appearing in the quadratic response function, and (iii) retrieving double-excitations through a real-time semiclassical approach to correlation in a model quantum dot. },
Author = {Peter Elliott and Sharma Goldson and Chris Canahui and Neepa T. Maitra},
Date-Added = {2019-11-06 20:52:35 +0100},
Date-Modified = {2019-11-06 20:52:35 +0100},
Date-Modified = {2019-11-19 19:09:46 +0100},
Doi = {http://dx.doi.org/10.1016/j.chemphys.2011.03.020},
Issn = {0301-0104},
Journal = {Chem. Phys.},
Keywords = {Adiabatic approximation},
Number = {1},
Pages = {110--119},
Title = {Perspectives on double-excitations in \{TDDFT\}},
Title = {Perspectives on double-excitations in TDDFT},
Url = {http://www.sciencedirect.com/science/article/pii/S0301010411000966},
Volume = {391},
Year = {2011},
@ -543,9 +593,10 @@
@article{Chr77,
Author = {Christiansen, P. A. and McCullough, E. A.},
Date-Added = {2019-11-03 21:52:57 +0100},
Date-Modified = {2019-11-03 21:52:57 +0100},
Date-Modified = {2019-11-19 19:25:20 +0100},
Journal = JCP,
Pages = {1877},
Pages = {1877--1882},
Title = {Numerical Hartree--Fock Calculations for N$_2$, FH, and CO: Comparison with Optimized LCAO Results},
Volume = 67,
Year = 1977}
@ -597,20 +648,20 @@
@article{Cur97,
Author = {Curtiss, L. A. and Raghavachari, K. and Referm, P. C. and Pople, J. A.},
Date-Added = {2019-11-03 14:35:45 +0100},
Date-Modified = {2019-11-03 14:36:44 +0100},
Date-Modified = {2019-11-19 19:22:53 +0100},
Journal = JCP,
Pages = {1063},
Title = {Assessment of Gaussian-2 and density functional theories for the computation of enthalpies of formation},
Pages = {1063--1079},
Title = {Assessment of Gaussian-2 and Density Functional Theories for the Computation of Enthalpies of Formation},
Volume = 106,
Year = 1997}
@article{Gar19,
Author = {Y. Garniron and K. Gasperich and T. Applencourt and A. Benali and A. Fert{\'e} and J. Paquier and B. Pradines and R. Assaraf and P. Reinhardt and J. Toulouse and P. Barbaresco and N. Renon and G. David and J. P. Malrieu and M. V{\'e}ril and M. Caffarel and P. F. Loos and E. Giner and A. Scemama},
Date-Added = {2019-11-03 13:55:48 +0100},
Date-Modified = {2019-11-03 13:56:02 +0100},
Date-Modified = {2019-11-19 19:30:25 +0100},
Doi = {10.1021/acs.jctc.9b00176},
Journal = {J. Chem. Theory Comput.},
Pages = {3591},
Pages = {3591--3609},
Title = {Quantum Package 2.0: A Open-Source Determinant-Driven Suite Of Programs},
Volume = {15},
Year = {2019},
@ -649,10 +700,10 @@
@article{Jac16,
Author = {D. Jacquemin and I. Duchemin and X. Blase},
Date-Added = {2019-11-02 22:34:05 +0100},
Date-Modified = {2019-11-02 22:34:11 +0100},
Date-Modified = {2019-11-19 19:29:46 +0100},
Doi = {10.1080/00268976.2015.1119901},
Journal = {Mol. Phys.},
Pages = {957},
Pages = {957--967},
Title = {Assessment Of The Convergence Of Partially Self-Consistent {{BSE/GW}} Calculations},
Volume = {114},
Year = {2016},
@ -704,10 +755,10 @@
@article{Loo20,
Author = {P. F. Loos and F. Lipparini and M. Boggio-Pasqua and A. Scemama and D. Jacquemin},
Date-Added = {2019-11-01 22:39:34 +0100},
Date-Modified = {2019-11-01 22:40:43 +0100},
Date-Modified = {2019-11-19 19:14:10 +0100},
Journal = {J. Chem. Theory Comput.},
Pages = {submitted},
Title = {Highly-Accurate Reference Excitation Energies and Benchmarks: Medium Size Molecules},
Title = {A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules},
Year = {2020}}
@article{Kan17,
@ -758,9 +809,9 @@
@article{Tro99,
Author = {A. B. Trofimov and G. Stelter and J. Schirmer},
Date-Added = {2019-10-31 15:04:29 +0100},
Date-Modified = {2019-10-31 15:05:20 +0100},
Date-Modified = {2019-11-19 19:29:09 +0100},
Journal = {J. Chem. Phys.},
Pages = {9982},
Pages = {9982--9999},
Title = {A Consistent Third-Order Propagator Method For Electronic Excitation},
Volume = {111},
Year = {1999}}
@ -768,9 +819,9 @@
@article{Sch82,
Author = {J. Schirmer},
Date-Added = {2019-10-31 15:02:19 +0100},
Date-Modified = {2019-10-31 15:03:19 +0100},
Date-Modified = {2019-11-19 19:28:42 +0100},
Journal = {Phys. Rev. A},
Pages = {2395},
Pages = {2395--2416},
Title = {Beyond The Random-Phase Approximation: a New Approximation Scheme For The Polarization Propagator},
Volume = {26},
Year = {1982}}
@ -778,7 +829,7 @@
@article{Sce14,
Author = {Scemama, A. and Applencourt, T. and Giner, E. and Caffarel, M.},
Date-Added = {2019-10-31 15:00:17 +0100},
Date-Modified = {2019-10-31 15:00:17 +0100},
Date-Modified = {2019-11-19 19:19:06 +0100},
Doi = {10.1063/1.4903985},
Issn = {1089-7690},
Journal = {J. Chem. Phys.},
@ -786,7 +837,7 @@
Number = {24},
Pages = {244110},
Publisher = {AIP Publishing},
Title = {Accurate nonrelativistic ground-state energies of 3d transition metal atoms},
Title = {Accurate Nonrelativistic Ground-state Energies of $3d$ Transition Metal Atoms},
Url = {http://dx.doi.org/10.1063/1.4903985},
Volume = {141},
Year = {2014},
@ -1023,13 +1074,13 @@
Abstract = {The general theory of analytic derivatives for the equation-of-motion coupled cluster (EOM-CC) method is reviewed. Special attention is paid to the EOM-CC singles and doubles (EOM-CCSD) approximation, which has the same computational scaling properties as the coupled-cluster singles doubles (CCSD) ground state method and is therefore applicable to a wide range of molecular systems. The detailed spin orbital equations that must be solved in EOM-CCSD gradient calculations are presented for the first time, and some guidelines are discussed regarding their computational implementation. Finally, use of the EOM-CCSD gradient method is illustrated by determining the structure, dipole moment components, harmonic frequencies and infrared intensities of formyl fluoride (HFCO) in its singlet excited (n, $\pi$*) state.},
Author = {Stanton, John F. and Gauss, J{\"u}rgen},
Date-Added = {2019-10-30 17:26:06 +0100},
Date-Modified = {2019-10-30 17:27:11 +0100},
Date-Modified = {2019-11-19 19:10:34 +0100},
Doi = {10.1007/BF01133076},
Issn = {1432-2234},
Journal = {Theor. Chim. Acta},
Number = {5},
Pages = {267--289},
Title = {Analytic energy derivatives for the equation-of-motion coupled-cluster method: Algebraic expressions, implementation and application to theS1 state of HFCO},
Title = {Analytic Energy Derivatives for the Equation-of-Motion Coupled-Cluster Method: Algebraic Expressions, Implementation and Application to the $S_1$ State of HFCO},
Url = {http://dx.doi.org/10.1007/BF01133076},
Volume = {91},
Year = {1995},
@ -1150,7 +1201,7 @@
@article{Hol17,
Author = {Holmes, Adam A. and Umrigar, C. J. and Sharma, Sandeep},
Date-Added = {2019-10-30 15:38:00 +0100},
Date-Modified = {2019-10-30 15:38:10 +0100},
Date-Modified = {2019-11-19 19:16:40 +0100},
Doi = {10.1063/1.4998614},
Issn = {1089-7690},
Journal = {J. Chem. Phys.},
@ -1158,7 +1209,7 @@
Number = {16},
Pages = {164111},
Publisher = {AIP Publishing},
Title = {Excited states using semistochastic heat-bath configuration interaction},
Title = {Excited States Using Semistochastic Heat-Bath Configuration Interaction},
Url = {http://dx.doi.org/10.1063/1.4998614},
Volume = {147},
Year = {2017},
@ -1709,16 +1760,6 @@
Year = {2019},
Bdsk-Url-1 = {https://doi.org/10.1021/acs.jctc.8b01103}}
@article{Loo19b,
Author = {Loos, Pierre-Francois and Jacquemin, Denis},
Date-Added = {2019-10-30 13:34:30 +0100},
Date-Modified = {2019-10-30 15:42:57 +0100},
Doi = {10.1002/cptc.201700090},
Journal = {ChemPhotoChem},
Title = {Evaluating 0-0 Energies with Theoretical Tools: a Short Review},
Year = {2019},
Bdsk-Url-1 = {https://doi.org/10.1002/cptc.201700090}}
@article{Loo19c,
Author = {Loos, Pierre-Fran{\c c}ois and Boggio-Pasqua, Martial and Scemama, Anthony and Caffarel, Michel and Jacquemin, Denis},
Date-Added = {2019-10-30 13:34:30 +0100},
@ -1876,6 +1917,7 @@
@article{Ish95,
Author = {Ishikawa, Naoto and Head-Gordon, Martin},
Date-Modified = {2019-11-19 19:09:19 +0100},
Doi = {10.1002/qua.560560845},
Issn = {0020-7608},
Journal = {Int. J. Quantum Chem.},
@ -1883,13 +1925,14 @@
Number = {S29},
Pages = {421--427},
Publisher = {John Wiley {\&} Sons, Ltd},
Title = {{Analytical gradient of the CIS(D) perturbative correction to single-excitation configuration interaction excited states}},
Title = {Analytical Gradient of the CIS(D) Perturbative Correction to Single-Excitation Configuration Interaction Excited States},
Volume = {56},
Year = {1995},
Bdsk-Url-1 = {https://doi.org/10.1002/qua.560560845}}
@article{Reh19,
Author = {Rehn, Dirk R. and Dreuw, Andreas},
Date-Modified = {2019-11-19 19:13:45 +0100},
Doi = {10.1063/1.5085117},
Issn = {1089-7690},
Journal = {J. Chem. Phys.},
@ -1897,20 +1940,21 @@
Number = {17},
Pages = {174110},
Publisher = {American Institute of Physics},
Title = {{Analytic nuclear gradients of the algebraic-diagrammatic construction scheme for the polarization propagator up to third order of perturbation theory}},
Title = {Analytic Nuclear Gradients of the Algebraic-Diagrammatic Construction Scheme for the Polarization Propagator up to Third Order of Perturbation Theory},
Volume = {150},
Year = {2019},
Bdsk-Url-1 = {https://doi.org/10.1063/1.5085117}}
@article{Sut05,
Author = {Herb Sutter and James Larus},
Date-Modified = {2019-11-19 19:31:04 +0100},
Doi = {10.1145/1095408.1095421},
Journal = {Queue},
Month = {sep},
Number = {7},
Pages = {54},
Pages = {54--62},
Publisher = {Association for Computing Machinery ({ACM})},
Title = {Software and the concurrency revolution},
Title = {Software and the Concurrency Revolution},
Url = {https://doi.org/10.1145%2F1095408.1095421},
Volume = {3},
Year = 2005,
@ -1919,6 +1963,7 @@
@article{Cle10,
Author = {Cleland, Deidre and Booth, George H. and Alavi, Ali},
Date-Modified = {2019-11-19 19:17:56 +0100},
Doi = {10.1063/1.3302277},
Issn = {0021-9606},
Journal = {J. Chem. Phys.},
@ -1926,13 +1971,14 @@
Number = {4},
Pages = {041103},
Publisher = {American Institute of Physics},
Title = {{Communications: Survival of the fittest: Accelerating convergence in full configuration-interaction quantum Monte Carlo}},
Title = {Communications: Survival of the Fittest: Accelerating Convergence in Full Configuration-Interaction Quantum Monte Carlo},
Volume = {132},
Year = {2010},
Bdsk-Url-1 = {https://doi.org/10.1063/1.3302277}}
@article{Val10,
Author = {Valiev, M. and Bylaska, E. J. and Govind, N. and Kowalski, K. and Straatsma, T. P. and Van Dam, H. J. J. and Wang, D. and Nieplocha, J. and Apra, E. and Windus, T. L. and de Jong, W. A.},
Date-Modified = {2019-11-19 19:17:31 +0100},
Doi = {10.1016/j.cpc.2010.04.018},
Issn = {0010-4655},
Journal = {Comput. Phys. Commun.},
@ -1940,7 +1986,7 @@
Number = {9},
Pages = {1477--1489},
Publisher = {North-Holland},
Title = {{NWChem: A comprehensive and scalable open-source solution for large scale molecular simulations}},
Title = {NWChem: A Comprehensive and Scalable Open-Source Solution for Large Scale Molecular Simulations},
Volume = {181},
Year = {2010},
Bdsk-Url-1 = {https://doi.org/10.1016/j.cpc.2010.04.018}}
@ -1961,6 +2007,7 @@
@article{Kri13,
Author = {Kristensen, Kasper and Kj{\ae}rgaard, Thomas and H{\o}yvik, Ida-Marie and Ettenhuber, Patrick and J{\o}rgensen, Poul and Jansik, Branislav and Reine, Simen and Jakowski, Jacek},
Date-Modified = {2019-11-19 19:18:28 +0100},
Doi = {10.1080/00268976.2013.783941},
Issn = {0026-8976},
Journal = {Mol. Phys.},
@ -1968,13 +2015,14 @@
Number = {9-11},
Pages = {1196--1210},
Publisher = {Taylor {\&} Francis},
Title = {{The divide{\textendash}expand{\textendash}consolidate MP2 scheme goes massively parallel}},
Title = {The Divide{\textendash}Expand{\textendash}Consolidate MP2 Scheme Goes Massively Parallel},
Volume = {111},
Year = {2013},
Bdsk-Url-1 = {https://doi.org/10.1080/00268976.2013.783941}}
@article{Sce13,
Author = {Scemama, Anthony and Caffarel, Michel and Oseret, Emmanuel and Jalby, William},
Date-Modified = {2019-11-19 19:19:35 +0100},
Doi = {10.1002/jcc.23216},
Issn = {0192-8651},
Journal = {J. Comput. Chem.},
@ -1982,7 +2030,7 @@
Number = {11},
Pages = {938--951},
Publisher = {John Wiley {\&} Sons, Ltd},
Title = {{Quantum Monte Carlo for large chemical systems: Implementing efficient strategies for petascale platforms and beyond}},
Title = {Quantum Monte Carlo for Large Chemical Systems: Implementing Efficient Strategies for Petascale Platforms and Beyond},
Volume = {34},
Year = {2013},
Bdsk-Url-1 = {https://doi.org/10.1002/jcc.23216}}
@ -2003,6 +2051,7 @@
@article{Kim18,
Author = {Kim, Jeongnim and Baczewski, Andrew D. and Beaudet, Todd D. and Benali, Anouar and Bennett, M. Chandler and Berrill, Mark A. and Blunt, Nick S. and Borda, Edgar Josu{\ifmmode\acute{e}\else\'{e}\fi} Landinez and Casula, Michele and Ceperley, David M. and Chiesa, Simone and Clark, Bryan K. and Iii, Raymond C. Clay and Delaney, Kris T. and Dewing, Mark and Esler, Kenneth P. and Hao, Hongxia and Heinonen, Olle and Kent, Paul R. C. and Krogel, Jaron T. and Kyl{\ifmmode\ddot{a}\else\"{a}\fi}np{\ifmmode\ddot{a}\else\"{a}\fi}{\ifmmode\ddot{a}\else\"{a}\fi}, Ilkka and Li, Ying Wai and Lopez, M. Graham and Luo, Ye and Malone, Fionn D. and Martin, Richard M. and Mathuriya, Amrita and McMinis, Jeremy and Melton, Cody A. and Mitas, Lubos and Morales, Miguel A. and Neuscamman, Eric and Parker, William D. and Flores, Sergio D. Pineda and Romero, Nichols A. and Rubenstein, Brenda M. and Shea, Jacqueline A. R. and Shin, Hyeondeok and Shulenburger, Luke and Tillack, Andreas F. and Townsend, Joshua P. and Tubman, Norm M. and Van Der Goetz, Brett and Vincent, Jordan E. and Yang, D. ChangMo and Yang, Yubo and Zhang, Shuai and Zhao, Luning},
Date-Modified = {2019-11-19 19:20:43 +0100},
Doi = {10.1088/1361-648x/aab9c3},
Issn = {0953-8984},
Journal = {J. Phys.: Condens. Matter},
@ -2010,13 +2059,14 @@
Number = {19},
Pages = {195901},
Publisher = {IOP Publishing},
Title = {{QMCPACK: an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids}},
Title = {QMCPACK: an Open Source ab initio Quantum Monte Carlo Package for the Electronic Structure of Atoms, Molecules and Solids},
Volume = {30},
Year = {2018},
Bdsk-Url-1 = {https://doi.org/10.1088/1361-648x/aab9c3}}
@article{Sny15,
Author = {Snyder, James W. and Hohenstein, Edward G. and Luehr, Nathan and Mart{\ifmmode\acute{\imath}\else\'{\i}\fi}nez, Todd J.},
Date-Modified = {2019-11-19 19:21:18 +0100},
Doi = {10.1063/1.4932613},
Issn = {0021-9606},
Journal = {J. Chem. Phys.},
@ -2024,7 +2074,7 @@
Number = {15},
Pages = {154107},
Publisher = {American Institute of Physics},
Title = {{An atomic orbital-based formulation of analytical gradients and nonadiabatic coupling vector elements for the state-averaged complete active space self-consistent field method on graphical processing units}},
Title = {An Atomic Orbital-Based Formulation of Analytical Gradients and Nonadiabatic Coupling Vector Elements for the State-Averaged Complete Active Space Self-Consistent Field Method on Graphical Processing Units},
Volume = {143},
Year = {2015},
Bdsk-Url-1 = {https://doi.org/10.1063/1.4932613}}
@ -2044,6 +2094,7 @@
@article{Kal17,
Author = {Kaliman, Ilya A. and Krylov, Anna I.},
Date-Modified = {2019-11-19 19:21:57 +0100},
Doi = {10.1002/jcc.24713},
Issn = {0192-8651},
Journal = {J. Comput. Chem.},
@ -2051,28 +2102,29 @@
Number = {11},
Pages = {842--853},
Publisher = {John Wiley {\&} Sons, Ltd},
Title = {{New algorithm for tensor contractions on multi-core CPUs, GPUs, and accelerators enables CCSD and EOM-CCSD calculations with over 1000 basis functions on a single compute node}},
Title = {New Algorithm for Tensor Contractions on Multi-core CPUs, GPUs, and Accelerators Enables CCSD and EOM-CCSD Calculations with over 1000 Basis Functions on a Single Compute Node},
Volume = {38},
Year = {2017},
Bdsk-Url-1 = {https://doi.org/10.1002/jcc.24713}}
@article{Sce13b,
Author = {Scemama, Anthony and Giner, Emmanuel},
Date-Modified = {2019-11-18 17:43:02 +0100},
Date-Modified = {2019-11-19 19:18:44 +0100},
Eprint = {1311.6244},
Journal = {arXiv},
Month = {Nov},
Title = {An efficient implementation of Slater-Condon rules},
Title = {An Efficient Implementation of Slater-Condon Rules},
Url = {https://arxiv.org/abs/1311.6244},
Year = {2013},
Bdsk-Url-1 = {https://arxiv.org/abs/1311.6244}}
@book{Pen19,
Author = {Peng, Ivy B. and Gokhale, Maya B. and Green, Eric W.},
Date-Modified = {2019-11-19 19:20:02 +0100},
Doi = {10.1145/3357526.3357568},
Isbn = {978-1-4503-7206-0},
Month = {Sep},
Publisher = {ACM},
Title = {{System evaluation of the Intel optane byte-addressable NVM}},
Title = {System Evaluation of the Intel Pptane Byte-Sddressable NVM},
Year = {2019},
Bdsk-Url-1 = {https://doi.org/10.1145/3357526.3357568}}

71
Manuscript/ExPerspective.tex
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@ -73,8 +73,8 @@
We provide a personal overview of the successive steps that made possible to obtain increasingly accurate excitation energies and properties with computational chemistry tools, eventually leading to chemically accurate vertical transition energies for small- and
medium-size molecules. First, we describe the evolution of \textit{ab initio} state-of-the-art methods employed to define benchmark values, with originally Roos' CASPT2 method, and then third-order coupled cluster methods as in the renowned Thiel set of excitation
energies described in a remarkable series of papers in the 2000's. More recently, this quest for highly accurate excitation energies was reinitiated thanks to the resurgence of selected configuration interaction (SCI) methods and their efficient parallel implementation.
These methods have been able to routinely deliver highly accurate excitation energies for small molecules, as well as medium-size molecules with compact basis sets for both single and double excitations. Second, we describe how these high-level methods
and the creation of large, diverse and accurate benchmark sets of excitation energies have allowed to assess fairly and accurately the performance of computationally lighter theoretical models (\eg, TD-DFT, BSE, ADC, EOM-CC, etc) for different types of
These methods have been able to routinely deliver highly accurate excitation energies for small molecules, as well as medium-size molecules with compact basis sets, for both single and double excitations. Second, we describe how these high-level methods
and the creation of large, diverse, and accurate benchmark sets of excitation energies have allowed to assess fairly and accurately the performance of computationally lighter theoretical models (\eg, TD-DFT, BSE, ADC, EOM-CC, etc.) for different types of
excited states ($\pi \ra \pi^*$, $n \ra \pi^*$, valence, Rydberg, singlet, triplet, double excitation, etc). We conclude this \textit{Perspective} by discussing the current potentiality of these methods from both an expert and a non-expert points of view, and what we
believe could be the future theoretical and technological developments in the field.
\end{abstract}
@ -89,7 +89,7 @@ The accurate modeling of excited-state properties with \textit{ab initio} quantu
photochemical processes. The factors that makes this quest for high accuracy particularly delicate are very diverse.
First of all (and maybe surprisingly), it is, in most cases, tricky to obtain reliable and accurate experimental data that one can straightforwardly compare to theoretical values. In the case of vertical excitation energies, \ie, excitation energies at a fixed geometry, band maxima
do not usually match theoretical values as one needs to take into account both geometric relaxation and zero-point vibrational energy motion. Even more problematic, experimental spectra might not be available in gas phase, and, in the worst-case scenario, no clear
do not usually correspond to theoretical values as one needs to take into account both geometric relaxation and zero-point vibrational energy motion. Even more problematic, experimental spectra might not be available in gas phase, and, in the worst-case scenario, no clear
assignment could be made. For a more faithful comparison between theory and experiment, although more computationally demanding, the so-called 0-0 energies are definitely a safer playground. \cite{Die04b,Win13,Fan14b,Loo19b}
Second, developing theories suited for excited states is usually more complex than their ground-state equivalent as a variational principle may not be available for excited states.
@ -159,13 +159,13 @@ This second-order correction greatly reduces the magnitude of the error compared
%%%%%%%%%%%%%%%%%%%
In the early 1990's, the complete-active-space self-consistent field (CASSCF) method \cite{And90} and its second-order perturbation-corrected variant CASPT2 \cite{And92} (both originally developed in Roos' group) appeared.
This was a real breakthrough.
Although it took more than ten years to obtain analytical nuclear gradients, \cite{Cel03} CASPT2 was probably the first method that could provide quantitative results for molecular excited states of genuine photochemical interest. \cite{Roo96}
Although it took more than ten years to obtain analytical gradients, \cite{Cel03} CASPT2 was probably the first method that could provide quantitative results for molecular excited states of genuine photochemical interest. \cite{Roo96}
Nonetheless, it is common knowledge that CASPT2 has the clear tendency of underestimating vertical excitation energies in organic molecules.
Driven by Angeli and Malrieu, \cite{Ang01} the creation of the second-order $n$-electron valence state perturbation theory (NEVPT2) method several years later was able to cure some of the main theoretical deficiencies of CASPT2.
For example, NEVPT2 is known to be intruder state free and size consistent.
The limited applicability of these multiconfigurational methods is mainly due to the need of carefully defining an active space based on the desired transition(s) in order to obtain meaningful results, as well as their factorial computational growth with the number of active electrons and orbitals.
We also point out that some emergent approaches, like DMRG (density matrix renormalization group), \cite{Bai19} also offer a new path for the development of these multiconfigurational theories.
With a typical minimal valence active space tailored for the desired transitions, the usual error in CASPT2 or NEVPT2 calculations is $0.1$--$0.2$ eV.
With a typical minimal valence active space tailored for the desired transitions, the usual error with CASPT2 or NEVPT2 calculations is $0.1$--$0.2$ eV.
%%%%%%%%%%%%%
%%% TDDFT %%%
@ -174,8 +174,8 @@ The advent of time-dependent density-functional theory (TD-DFT) \cite{Run84,Cas9
For low-lying valence excited states, TD-DFT calculations relying on hybrid exchange-correlation functionals have a typical error of $0.2$--$0.4$ eV.
However, a large number of shortcomings were quickly discovered. \cite{Toz98,Toz99,Dre04,Mai04,Dre05,Lev06,Eli11}
In the present context, one of the most annoying feature of TD-DFT --- in its most standard (adiabatic) approximation --- is its inability to describe, even qualitatively, charge-transfer states, \cite{Toz99,Dre04} Rydberg states, \cite{Toz98} and double excitations. \cite{Mai04,Lev06,Eli11}
One of the main related issues is the selection of the exchange-correlation functional from an ever-growing zoo of functionals and the variation of the excitation energies that one can observe with different functionals. \cite{Goe19,Sue19}
More specifically, despite the development of new, more robust approaches (including the so-called double hybrids \cite{Goe10a,Bre16,Sch17}), it is still difficult (not to say impossible) to select a functional adequate for all families of transitions. \cite{Lau13}
One closely related issue is the selection of the exchange-correlation functional from an ever-growing zoo of functionals and the variation of the excitation energies that one can observe with different functionals. \cite{Goe19,Sue19}
More specifically, despite the development of new, more robust approaches (including the so-called range-separated \cite{Sav96,IIk01,Yan04,Vyd06} and double \cite{Goe10a,Bre16,Sch17} hybrids), it is still difficult (not to say impossible) to select a functional adequate for all families of transitions. \cite{Lau13}
Moreover, the difficulty of making TD-DFT systematically improvable obviously hampers its applicability.
Despite all of this, TD-DFT remains nowadays the most employed excited-state method in the electronic structure community (and beyond).
@ -189,7 +189,7 @@ Its third-order version, EOM-CCSDT, was also implemented and provides, at a sign
Although extremely expensive and tedious to implement, higher orders are also technically possible for small systems thanks to automatically generated code. \cite{Kuc91,Hir04}
For the sake of brevity, we drop the EOM acronym in the rest of this \textit{Perspective} keeping in mind that these CC methods are applied to excited states in the present context.
The CC family of methods was quickly followed by an approximated and computationally lighter family with, in front line, the second-order CC2 model \cite{Chr95} and its third-order extension, CC3. \cite{Chr95b}
The original CC family of methods was quickly completed by an approximated and computationally lighter family with, in front line, the second-order CC2 model \cite{Chr95} and its third-order extension, CC3. \cite{Chr95b}
As a $N^7$ method (where $N$ is the number of basis functions), CC3 has a particularly interesting accuracy/cost ratio with errors usually below the chemical accuracy threshold. \cite{Hat05c,Loo18a,Loo18b,Loo19a}
The series CC2, CCSD, CC3, CCSDT defines a hierarchy of models with $N^5$, $N^6$, $N^7$ and $N^8$ scaling, respectively.
It is also noteworthy that CCSDT and CC3 are also able to detect the presence of double excitations, a feature that is absent from both CCSD and CC2. \cite{Loo19c}
@ -197,29 +197,29 @@ It is also noteworthy that CCSDT and CC3 are also able to detect the presence of
%%%%%%%%%%%%%%%%%%%
%%% ADC METHODS %%%
%%%%%%%%%%%%%%%%%%%
It is also important to mention the recent rejuvenation of the second- and third-order algebraic diagrammatic construction [ADC(2) \cite{Sch82} and ADC(3) \cite{Tro99,Har14}] which scale as $N^5$ and $N^6$, respectively.
It is also important to mention the recent rejuvenation of the second- and third-order algebraic diagrammatic construction [ADC(2) \cite{Sch82} and ADC(3) \cite{Tro99,Har14}] methods that scale as $N^5$ and $N^6$, respectively.
This renaissance was certainly initiated by the enormous amount of work invested by Dreuw's group in order to provide a fast and efficient implementation of these methods, \cite{Dre15} including the analytical gradients, \cite{Reh19} as well as other interesting variants.
These Green's function one-electron propagator techniques represent interesting alternatives thanks to their reduced scaling compared to their CC equivalents.
These Green's function one-electron propagator techniques indeed represent valuable alternatives thanks to their reduced cost compared to their CC equivalents.
In that regard, ADC(2) is particularly attractive with an error around $0.1$--$0.2$ eV.
However, we have recently observed that ADC(3) generally overcorrects the ADC(2) excitation energies and is significantly less accurate than CC3. \cite{Tro02,Loo18a,Loo20}
%%%%%%%%%%%%%%
%%% BSE@GW %%%
%%%%%%%%%%%%%%
Finally, let us mention the many-body Green's function Bethe-Salpeter equation (BSE) formalism \cite{Str88} (which is usually performed on top of a \emph{GW} calculation \cite{Hed65}).
BSE has gained momentum in the past few years and is a serious candidate as a computationally inexpensive electronic structure theory method that can model accurately excited states (with a typical error of $0.1$--$0.3$ eV) and some of the corresponding properties. \cite{Jac17b,Bla18}
Finally, let us mention the many-body Green's function Bethe-Salpeter equation (BSE) formalism \cite{Str88} (which is usually performed on top of a \emph{GW} calculation). \cite{Hed65}
BSE has gained momentum in the past few years and is a serious candidate as a computationally inexpensive electronic structure theory method that can effectively model excited states with a typical error of $0.1$--$0.3$ eV, as well as some related properties. \cite{Jac17b,Bla18}
One of the main advantage of BSE compared to TD-DFT (with a similar computational cost) is that it allows a faithful description of charge-transfer states and, when performed on top of a (partially) self-consistently \emph{GW} calculation, BSE@\emph{GW} has been shown to be weakly dependent on its starting point (\ie, on the functional selected for the underlying DFT calculation). \cite{Jac16,Gui18}
However, due to the adiabatic (\ie, static) approximation, doubly excited states are completely absent from the BSE spectrum.
%%%%%%%%%%%%%%%%%%%
%%% SCI METHODS %%%
%%%%%%%%%%%%%%%%%%%
In the past five years, \cite{Gin13,Gin15} we have witnessed a resurgence of the so-called selected CI (SCI) methods \cite{Ben69,Whi69,Hur73} thanks to the development and implementation of new, fast and efficient algorithms to select cleverly determinants in the full CI (FCI) space (see Refs.~\onlinecite{Gar18,Gar19} and references therein).
In the past five years, \cite{Gin13,Gin15} we have witnessed a resurgence of the so-called selected CI (SCI) methods \cite{Ben69,Whi69,Hur73} thanks to the development and implementation of new, fast, and efficient algorithms to select cleverly determinants in the full CI (FCI) space (see Refs.~\onlinecite{Gar18,Gar19} and references therein).
SCI methods rely on the same principle as the usual CI approach, except that determinants are not chosen \textit{a priori} based on occupation or excitation criteria but selected among the entire set of determinants based on their estimated contribution to the FCI wave function or energy.
Indeed, it has been noticed long ago that, even inside a predefined subspace of determinants, only a small number of them significantly contributes.
The main advantage of SCI methods is that no a priori assumption is made on the type of electron correlation.
Therefore, at the price of a brute force calculation, a SCI calculation is less biased by the user appreciation of the problem's complexity.
One of the strength of one of the implementation, based on the CIPSI (configuration interaction using a perturbative selection made iteratively) algorithm developed by Huron, Rancurel, and Malrieu in 1973 \cite{Hur73} is its parallel efficiency which makes possible to run on thousands of CPU cores. \cite{Gar19}
The main advantage of SCI methods is that no \textit{a priori} assumption is made on the type of electron correlation.
Therefore, at the price of a brute force calculation, a SCI calculation is not, or at least less, biased by the user appreciation of the problem's complexity.
One of the strength of one of the implementation, based on the CIPSI (configuration interaction using a perturbative selection made iteratively) algorithm developed by Huron, Rancurel, and Malrieu \cite{Hur73} is its parallel efficiency which makes possible to run on thousands of CPU cores. \cite{Gar19}
Thanks to these tremendous features, SCI methods deliver near FCI quality excitation energies for both singly and doubly excited states, \cite{Hol17,Chi18,Loo18a,Loo19c} with an error of roughly $0.03$ eV, mostly originating from the extrapolation procedure. \cite{Gar19}
However, although the \textit{``exponential wall''} is pushed back, this type of method is only applicable to molecules with a small number of heavy atoms and/or relatively compact basis sets.
@ -284,10 +284,10 @@ For excited states, things started moving a little later but some major contribu
%%%%%%%%%%%%%%%%%%%
%%% THIEL'S SET %%%
%%%%%%%%%%%%%%%%%%%
One of these major contributions was provided by the group of Walter Thiel \cite{Sch08,Sil08,Sau09,Sil10b,Sil10c} with the introduction of the so-called Thiel set of excitation energies. \cite{Sch08}
For the first time, this set was large, diverse and accurate enough to be used as a proper benchmarking set for excited-state methods.
More specifically, it gathers a large number of excitation energies consisting of 28 medium-size organic molecules with a total of 223 valence excited states (152 singlet and 71 triplet states).
In their first study they performed CC2, CCSD, CC3 and CASPT2 calculations (with the TZVP basis) in order to provide (based on additional high-level literature data) a list of best theoretical estimates (TBEs) for all these transitions.
One of these major contributions was provided by the group of Walter Thiel \cite{Sch08,Sil08,Sau09,Sil10b,Sil10c} with the introduction of the so-called Thiel (Mulheim) set of excitation energies. \cite{Sch08}
For the first time, this set was large, diverse, consistent, and accurate enough to be used as a proper benchmarking set for excited-state methods.
More specifically, it gathers a large number of excitation energies consisting of 28 medium-size organic molecules with a total of 223 valence excited states (152 singlet and 71 triplet states) for which theoretical best estimates (TBEs) were defined.
In their first study Thiel and collaborators performed CC2, CCSD, CC3 and CASPT2 calculations (with the TZVP basis) in order to provide (based on additional high-level literature data) TBEs for these transitions.
Their main conclusion was that \textit{``CC3 and CASPT2 excitation energies are in excellent agreement for states which are dominated by single excitations''}.
These TBEs were quickly refined with the larger \emph{aug}-cc-pVTZ basis set, \cite{Sil10b} highlighting the importance of diffuse functions.
As a direct evidence of the actual value of reference data, these TBEs were quickly picked up to benchmark various computationally effective methods from semi-empirical to state-of-the-art \textit{ab initio} methods (see the Introduction of Ref.~\onlinecite{Loo18a} and references therein).
@ -303,33 +303,34 @@ These two studies clearly demonstrate and motivate the need for higher accuracy
%%%%%%%%%%%%%%%%%%%%%%%
%%% JACQUEMIN'S SET %%%
%%%%%%%%%%%%%%%%%%%%%%%
Recently, we made, what we think, is a significant contribution to this quest for highly accurate excitation energies. \cite{Loo18a}
Recently, we made, what we think, is a significant contribution to this quest for highly accurate vertical excitation energies. \cite{Loo18a}
More specifically, we studied 18 small molecules with sizes ranging from one to three non-hydrogen atoms.
For such systems, using a combination of high-order CC methods, SCI calculations and large diffuse basis sets, we were able to compute a list of 110 highly accurate vertical excitation energies for excited states of various natures (valence, Rydberg, $n \ra \pi^*$, $\pi \ra \pi^*$, singlet, triplet and doubly excited) based on accurate CC3/\emph{aug}-cc-pVTZ geometries.
For such systems, using a combination of high-order CC methods, SCI calculations and large diffuse basis sets, we were able to compute a list of 110 highly accurate vertical excitation energies for excited states of various natures (valence, Rydberg, $n \ra \pi^*$, $\pi \ra \pi^*$, singlet, triplet and doubly excited) based on CC3/\emph{aug}-cc-pVTZ geometries.
In the following, we label this set of TBEs as {\SetA}.
Importantly, it allowed us to benchmark a series of popular excited-state wave function methods accounting for double and triple excitations (see Fig.~\ref{fig:Set1}): CIS(D), CC2, CCSD, STEOM-CCSD, \cite{Noo97} CCSDR(3), \cite{Chr77} CCSDT-3, \cite{Wat96} CC3, ADC(2), and ADC(3).
Our main conclusion was that CC3 is extremely accurate (with a mean absolute error of only $\sim 0.03$ eV), and that, although less accurate than CC3, CCSDT-3 could be used as a reliable reference for benchmark studies.
Importantly, it allowed us to benchmark a series of popular excited-state wave function methods partially or fully accounting for double and triple excitations (see Fig.~\ref{fig:Set1}): CIS(D), CC2, CCSD, STEOM-CCSD, \cite{Noo97} CCSDR(3), \cite{Chr77} CCSDT-3, \cite{Wat96} CC3, ADC(2), and ADC(3).
Our main conclusion was that CC3 is extremely accurate (with a mean absolute error of only $\sim 0.03$ eV), and that, although slightly less accurate than CC3, CCSDT-3 could be used as a reliable reference for benchmark studies.
Quite surprisingly, ADC(3) was found to have a clear tendency to overcorrect its second-order version ADC(2).
The mean absolute errors (MAEs) obtained for this set can be found in Fig.~\ref{fig:Set1}.
In a second study, \cite{Loo19c} using a similar combination of theoretical models (but mostly extrapolated SCI energies), we provided accurate reference excitation energies for transitions involving a substantial amount of double excitations using a series of increasingly large diffuse-containing atomic basis sets (up to \emph{aug}-cc-pVQZ when technically feasible).
This set gathers 20 vertical transitions from 14 small- and medium-sized molecules, a set we label as {\SetB} in the remaining of this \emph{Perspective}.
An important addition to this second study was the computation of double excitations with various flavors of multiconfigurational methods (CASSCF, CASPT2, and NEVPT2) in addition to high-order CC methods including, at least, perturbative or iterative triple corrections (see Fig.~\ref{fig:Set2}).
An important addition to this second study was the evaluation of various flavors of multiconfigurational methods (CASSCF, CASPT2, and NEVPT2) in addition to high-order CC methods including, at least, perturbative triples (see Fig.~\ref{fig:Set2}).
Our results clearly evidence that the error in CC methods is intimately related to the amount of double-excitation character in the vertical transition.
For ``pure'' double excitations (\ie, for transitions which do not mix with single excitations), the error in CC3 and CCSDT can easily reach $1$ and $0.5$ eV, respectively, while it goes down to a few tenths of an electronvolt for more common transitions (such as in \emph{trans}-butadiene and benzene) involving a significant amount of singles.\cite{Shu17,Bar18b,Bar18a}
The quality of the excitation energies obtained with multiconfigurational methods was harder to predict as the overall accuracy of these methods is highly dependent on both the system and the selected active space.
Nevertheless, CASPT2 and NEVPT2 were found to be more accurate for transition with a small percentage of single excitations (error usually below $0.1$ eV) than for excitations dominated by single excitations where the error is more around $0.1$--$0.2$ eV (see Fig.~\ref{fig:Set2}).
Nevertheless, CASPT2 and NEVPT2 were found to be more accurate for transition with a small percentage of single excitations (error usually below $0.1$ eV) than for excitations dominated by single excitations where the error is closer from $0.1$--$0.2$ eV (see Fig.~\ref{fig:Set2}).
In our latest study, \cite{Loo20} in order to provide more general conclusions, we generated highly accurate vertical transition energies for larger compounds with a set composed by 27 organic molecules encompassing from four to six non-hydrogen atoms for a total of 223 vertical transition energies of various natures.
This set, labeled as {\SetC} and still based on CC3/\emph{aug}-cc-pVTZ geometries, is constituted by a reasonably good balance of singlet, triplet, valence, and Rydberg states.
To obtain this new, larger set of TBEs, we employed CC methods up to the highest possible order (CC3, CCSDT, and CCSDTQ), very large SCI calculations (with up to hundred million determinants), as well as the most robust multiconfigurational method, NEVPT2.
Each approach was applied in combination with diffuse-containing atomic basis sets.
For all the transitions of the {\SetC} set, we reported at least CC3/\emph{aug}-cc-pVQZ transition energies as well as CC3/\emph{aug}-cc-pVTZ oscillator strengths for each dipole-allowed transition.
For all the transitions of the {\SetC} set, we reported at least CCSDT/\emph{aug}-cc-pVTZ (sometimes with basis set extrapolation) and CC3/\emph{aug}-cc-pVQZ transition energies as well as CC3/\emph{aug}-cc-pVTZ oscillator strengths for each dipole-allowed transition.
Pursuing our previous benchmarking efforts, \cite{Loo18a,Loo19c} we confirmed that CC3 almost systematically delivers transition energies in agreement with higher-level theoretical models ($\pm 0.04$ eV) except for transitions presenting a dominant double excitation character (see Fig.~\ref{fig:Set3}).
This settles down, at least for now, the debate by demonstrating the superiority of CC3 (in terms of accuracy) compared to methods like CCSDT-3 or ADC(3).
Moreover, thanks to the exhaustive and detailed comparisons made in Ref.~\onlinecite{Loo20}, we could safely conclude that CC3 also regularly outperforms CASPT2 (which underestimates excitation energies) and NEVPT2 (which overestimates excitation energies) as long as the corresponding transition does not show any strong multiple excitation character.
This settles down, at least for now, the debate by demonstrating the superiority of CC3 (in terms of accuracy) compared to methods like CCSDT-3 or ADC(3), see Fig.~\ref{fig:Set3}.
Moreover, thanks to the exhaustive and detailed comparisons made in Ref.~\onlinecite{Loo20}, we could safely conclude that CC3 also regularly outperforms CASPT2 (which often underestimates excitation energies) and NEVPT2 (which typically overestimates excitation energies) as long as the corresponding transition does not show any strong multiple excitation character.
Our current efforts are now focussing on expanding and merging these sets to create an complete test set of highly accurate excitations energies.
In particular, we are currently generating reference excitations energies for radicals as well as more ``exotic'' molecules containing heavier atoms (such as \ce{Cl}, \ce{F}, \ce{P}, and \ce{Si}). \cite{Loo20b}
In particular, we are currently generating reference excitations energies for radicals as well as more ``exotic'' molecules containing heavier atoms (such as \ce{Cl}, \ce{P}, and \ce{Si}). \cite{Loo20b}
The combination of these various sets would potentially create an ensemble of more than 400 vertical transition energies for small- and medium-size molecules based on accurate ground-state geometries.
Such a set would definitely be a valuable asset for the entire electronic structure community.
It would likely stimulate further theoretical developments in excited-state methods and provide a fair ground for the assessments of the currently available and under development excited-state models.
@ -337,12 +338,12 @@ It would likely stimulate further theoretical developments in excited-state meth
%%%%%%%%%%%%%%%%%%
%%% Properties
%%%%%%%%%%%%%%%%%%
Besides all the studies described above aiming at reaching chemically accurate vertical transition energies, it should be pointed out that an increasing amount of effort is now devoted to the obtention of highly-trustable excited-state properties.
Besides all the studies described above aiming at reaching chemically accurate vertical transition energies, it should be pointed out that an increasing amount of effort is currently devoted to the obtention of highly-trustable excited-state properties.
This includes, first, 0-0 energies, \cite{Die04b,Hat05c,Goe10a,Sen11b,Win13,Fan14b,Loo18b,Loo19a,Loo19b} which, as mentioned above, offer well-grounded comparisons with experiment.
However, because 0-0 energies are fairly insensitive to the underlying molecular geometries, \cite{Sen11b,Win13,Loo19a} they are not a good indicator of their overall quality.
Consequently, one can find in the literature several sets of excited-state geometries obtained at various levels of theory. \cite{Pag03,Gua13,Bou13,Tun16,Bud17}
Some of them are determined using state-of-the-art models, \cite{Gua13,Bud17} and also investigate the accuracy of the nuclear gradients at the Franck-Condon point. \cite{Taj18,Taj19}
The interested researcher may also find useful several investigations reporting sets of reference oscillator strengths. \cite{Sil10c,Har14,Kan14,Loo18a,Loo20b}
Consequently, one can find in the literature several sets of excited-state geometries obtained at various levels of theory, \cite{Pag03,Gua13,Bou13,Tun16,Bud17} some of them are determined using state-of-the-art models. \cite{Gua13,Bud17}
There are also investigations of the accuracy of the nuclear gradients at the Franck-Condon point. \cite{Taj18,Taj19}
The interested researcher may find useful several investigations reporting sets of reference oscillator strengths. \cite{Sil10c,Har14,Kan14,Loo18a,Loo20b}
More complex properties, such as two-photon cross-sections and vibrations, have been mostly determined at lower levels of theory, hinting at future studies on this particular subject.
%%%%%%%%%%%%%%%%%%
@ -351,7 +352,7 @@ More complex properties, such as two-photon cross-sections and vibrations, have
As concluding remarks, we would like to highlight once again the major contribution brought by Roos' and Thiel's groups in an effort to define benchmark values for excited states.
Following their footsteps, we have recently proposed a larger, even more accurate set of vertical transitions energies for various types of excited states (including double excitations). \cite{Loo18a,Loo19c,Loo20}
This was made possible thanks to a technological renaissance of SCI methods which can now routinely produce near-FCI excitation energies for small- and medium-size organic molecules. \cite{Chi18,Gar18,Gar19}
We hope that new technological advances will enable us to push further in years to come our quest to highly accurate excitation energies, and, importantly, of excited-state properties.
We hope that new technological advances will enable us to push further in years to come our quest to highly accurate excitation energies, and, importantly, of other excited-state properties.
%%%%%%%%%%%%%%%%%%%%%%%%
%%% ACKNOWLEDGEMENTS %%%