## Presentation

The LCPQ is based at the University of Toulouse. The research at LCPQ covers a large variety of topics dedicated to Theoretical-mostly Quantum- Chemistry and Theoretical Molecular Physics. The LCPQ is member of IRSAMC (The Institute of Research on Complex Atomic and Molecular Systems).

Before 2007 => Look at The Quantum Physics Laboratory HAL-LPQ.

## Research teams in the lab

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## New submit

### Last submission

[hal-02403471] A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules  (07/02/2020)
Following our previous work focussing on compounds containing up to 3 non-hydrogen atoms [\emph{J. Chem. Theory Comput.} {\bfseries 14} (2018) 4360--4379], we present here highly-accurate vertical transition energies obtained for 27 molecules encompassing 4, 5, and 6 non-hydrogen atoms. To obtain these energies, we use equation-of-motion coupled cluster theory up to the highest technically possible excitation order for these systems (CC3, EOM-CCSDT, and EOM-CCSDTQ), selected configuration interaction (SCI) calculations (with tens of millions of determinants in the reference space), as well as the multiconfigurational $n$-electron valence state perturbation theory (NEVPT2) method. All these approaches are applied in combination with diffuse-containing atomic basis sets. For all transitions, we report at least CC3/\emph{aug}-cc-pVQZ vertical excitation energies as well as CC3/\emph{aug}-cc-pVTZ oscillator strengths for each dipole-allowed transition. We show that CC3 almost systematically delivers transition energies in agreement with higher-level methods with a typical deviation of $\pm 0.04$ eV, except for transitions with a dominant double excitation character where the error is much larger. The present contribution gathers a large, diverse and accurate set of more than 200 highly-accurate transition energies for states of various natures (valence, Rydberg, singlet, triplet, $n \rightarrow \pi^*$, $\pi \rightarrow \pi^*$, \ldots). We use this series of theoretical best estimates to benchmark a series of popular methods for excited state calculations: CIS(D), ADC(2), CC2, STEOM-CCSD, EOM-CCSD, CCSDR(3), CCSDT-3, CC3, as well as NEVPT2. The results of these benchmarks are compared to the available literature data.

[hal-02088494] Influence of Pseudopotentials on Excitation Energies From Selected Configuration Interaction and Diffusion Monte Carlo  (05/02/2020)
[hal-02127513] Theoretical Rationalization of the Dual Photophysical Behavior of C60+  (05/02/2020)
[hal-01396539] Theoretical mechanistic study of self-sensitized photo-oxygenation and singlet oxygen thermal release in a dimethyldihydropyrene derivative  (06/02/2020)
[hal-01945031] Reference Energies for Double Excitations  (05/02/2020)