## Presentation

The LPT is based at the University of Toulouse. It has been founded in 1991 and its administrative structure was established in 2003. Before 2003, researchers where rassembled in the Group of Theoretical Physics. This group was hosted by the Laboratoire de Physique Quantique (now LCPQ).

The LPT is member of IRSAMC (The Institute of Research on Complex Atomic and Molecular Systems).

=> There publications before 2003: HAL-LPQ_GPT

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## Last submission

### [hal-02928385] Potential energy surfaces without unphysical discontinuities: the Coulomb-hole plus screened exchange approach

(9/9/20)
In this work we show the advantages of using the Coulomb-hole plus screened-exchange (COHSEX) approach in the calculation of potential energy surfaces. In particular, we demonstrate that, unlike perturbative $GW$ and partial self-consistent $GW$ approaches, such as eigenvalue-self-consistent $GW$ and quasi-particle self-consistent $GW$, the COHSEX approach yields smooth potential energy surfaces without irregularities and discontinuities. Moreover, we show that the ground-state potential energy surfaces (PES) obtained from the Bethe-Salpeter equation, within the adiabatic connection fluctuation dissipation theorem, built with quasi-particle energies obtained from perturbative COHSEX on top of Hartree-Fock (BSE@COHSEX@HF) yield very accurate results for diatomic molecules close to their equilibrium distance. When self-consistent COHSEX quasi-particle energies and orbitals are used to build the BSE equation the results become independent of the starting point. We show that self-consistency worsens the total energies but improves the equilibrium distances with respect to BSE@COHSEX@HF. This is mainly due to changes in the screening inside the BSE.

(9/13/20)

(9/9/20)

(7/17/20)

(7/17/20)