Statut  Confirmé 
Série  IPNTHEO 
Domaines  nuclth 
Date  Mercredi 13 Décembre 2017 
Heure  11:30 
Institut  IPN 
Salle  Bâtiment 100, Salle A015 
Nom de l'orateur  Tichai 
Prenom de l'orateur  Alexander 
Addresse email de l'orateur  
Institution de l'orateur  CEA Saclay ESNT/DPHN 
Titre  ManyBody Perturbation Theory for Ab Initio Nuclear Structure 
Résumé  The reach of ab initio calculations has extended significantly over the past years. In particular systems revealing a closedshell character can be described efficiently up to the tin isotopic chain via controlled manybody expansions like coupledcluster the ory, the inmedium similarity renormalization group or selfconsistent Green func tion techniques. However, the transfer of such methods to openshell nuclei requires a highly nontrivial extension. In this talk we will discuss manybody perturbation theory (MBPT) as a lightweighted alternative and give a pedestrian introduction to MBPT based on a HartreeFock reference state. Loworder energy corrections for ground states of closedshell nuclei will be discussed using stateoftheart chiral interactions. The conceptual simplicity of MBPT allows for a direct generalization to openshell systems by using correlated reference states. First I will present a MBPT version us ing a multiconfigurational reference state arising from a prior nocore shellmodel calculation (NCSM). We present recent calculations of secondorder energy correc tions of spectra of even and odd carbon and oxygen isotopes and compare them to exact diagonalizations from largescale NCSM calculations. Additionally, we will provide first results on the dripline physics of the fluorine isotopic chain. In a complementary ansatz we use symmetrybroken reference states from a Hartree FockBogoliubov (HFB) calculation as starting point for the correlation expansion and reformulate MBPT in a quasiparticle setting yielding the socalled Bogoliubov MBPT (BMBPT). We present preliminary results for the oxygen chain and compare them to other stateoftheart manybody approaches and provide an outlook on future applications of symmetrybroken manybody approaches. 
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