ISTPC is an international two-week summer school in electronic structure theory whose first edition was held in June 2015 (in Aussois, France). Since then, it has been organized twice in person (in 2017 and 2022) and once online (in 2021). The main topic of the school is electron correlation in physics and chemistry, with a particular focus on the formal aspects of standard and emerging electronic structure methods. The many-electron problem is the common denominator to all the lectures. It will be described, for ground and excited states, both in molecular and extended systems, with a multiple set of concepts that come from both the quantum chemistry and the solid-state physics communities. Both model and ab initio approaches will be covered.

The strongly multidisciplinary program of the school, which is a specificity of the ISTPC, echoes recent methodological efforts that often take place at the frontier between quantum chemistry and condensed matter physics, but also mathematics and, more recently, quantum computing. We can mention, for example, density functional theory (DFT) [1], its extension to excited states [2] and combination with many-electron wave functions [3-5]; one-electron reduced density matrix functional theory used as a reference frame from which, for example, the description of charged electronic excitations can be improved [6-7,31,32] and in-principle-exact complement to simpler seniority-zero (i.e., with empty or doubly-occupied orbitals only in the configuration expansion) electronic wave functions can be designed [8]; density matrix embedding theory [9], its mathematical construction [10-12] and connection to DFT [13-15]; Green function methods [29,30] and their implementation in quantum chemistry [16-20]; Wave function theory of electronic excitations, with a particular focus on orbital optimization [21-23]; and finally the adaptation of quantum chemical methods to quantum algorithmics [24-28].

Important practical information: Participants are expected to pay a registration fee, which should not exceed 950€ and will cover food and accommodation expenses at the center Paul Langevin in Aussois for the entire duration of the school. The total number of participants is limited to 40.