## Presentation

L’IRSAMC (The Institute of Research on Complex Atomic and Molecular Systems) is a federation of four laboratories (LCAR, LCPQ, LPCNO, LPT), in physics and fundamental chemistry whose research activities are supported both by the Université Paul Sabatier, the CNRS and INSA

## Publications of 4 research laboratories

• Hal-LCAR. - Laboratory Collisions Clusters Reactivity, from 1990 until todays
• Hal-LCPQ. - Quantum Chemistry and Physics Laboratory, from 2007 until todays
• Hal-LPCNO. - Physics and Chemistry of Nano Objects Laboratory, from 2006 until todays
• Hal-LPT.- Theoretical Physics Laboratory, from 2003 until todays

## Main advantages and functioning of Hal

• Long-term archiving, sustainability of the deposits
• Better visibility of the scientific productivity
• Open access, accessible everywhere
• Possibility of establishing lists of publications

Functioning

• The deposit of a document requires the agreement of its authors, and it must respect editor policy.
• If no agreement has been spent, deposit only the bibliographical note
• Beware ! Once a document is put online, it cannot be withdrawn. New versions may be added.

## Last submission

### [hal-03032753] QUESTDB: a database of highly-accurate excitation energies for the electronic structure community

(01/12/2020)
We describe our efforts of the past few years to create a large set of more than 500 highly-accurate vertical excitation energies of various natures ($\pi \to \pi^*$, $n \to \pi^*$, double excitation, Rydberg, singlet, doublet, triplet, etc) in small- and medium-sized molecules. These values have been obtained using an incremental strategy which consists in combining high-order coupled cluster and selected configuration interaction calculations using increasingly large diffuse basis sets in order to reach high accuracy. One of the key aspect of the so-called QUEST database of vertical excitations is that it does not rely on any experimental values, avoiding potential biases inherently linked to experiments and facilitating theoretical cross comparisons. Following this composite protocol, we have been able to produce theoretical best estimate (TBEs) with the aug-cc-pVTZ basis set for each of these transitions, as well as basis set corrected TBEs (i.e., near the complete basis set limit) for some of them. The TBEs/aug-cc-pVTZ have been employed to benchmark a large number of (lower-order) wave function methods such as CIS(D), ADC(2), CC2, STEOM-CCSD, CCSD, CCSDR(3), CCSDT-3, ADC(3), CC3, NEVPT2, and others (including spin-scaled variants). In order to gather the huge amount of data produced during the QUEST project, we have created a website [https://lcpq.github.io/QUESTDB_website] where one can easily test and compare the accuracy of a given method with respect to various variables such as the molecule size or its family, the nature of the excited states, the type of basis set, etc. We hope that the present review will provide a useful summary of our effort so far and foster new developments around excited-state methods.

(01/12/2020)

(28/11/2020)

(01/12/2020)

(26/11/2020)