# Nuclear collective excitations using correlated realistic interactions: The role of explicit random-phase approximation correlations

## Abstract

We examine to what extent correlated realistic nucleon-nucleon interactions, derived within the unitary correlation operator method (UCOM), can describe nuclear collective motion in the framework of first-order random-phase approximation (RPA). To this end we employ the correlated Argonne V18 interaction in calculations within the so-called ''Extended'' RPA (ERPA) and investigate the response of closed-shell nuclei. The ERPA is a renormalized RPA version which considers explicitly the depletion of the Fermi sea due to long-range correlations and thus allows us to examine how these affect the excitation spectra. It is found that the effect on the properties of giant resonances is rather small. Compared to the standard RPA, where excitations are built on top of the uncorrelated Hartree-Fock (HF) ground state, their centroid energies decrease by up to 1 MeV, approximately, in the isovector channel. The isoscalar response is less affected in general. Thus, the disagreement between our previous UCOM-based RPA calculations and the experimental data are to be attributed to other effects, namely to residual three-body terms in the Hamiltonian and to higher-order configurations. Single-particle energies and occupation probabilities obtained within the ERPA are compared with corresponding HF and perturbation-theory results and are discussed as well. The ERPA formalism ismore »

- Authors:

- Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstr. 9, D-64289 Darmstadt (Germany)

- Publication Date:

- OSTI Identifier:
- 20990949

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.75.014310; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; COLLECTIVE EXCITATIONS; GIANT RESONANCE; GROUND STATES; HAMILTONIANS; HARTREE-FOCK METHOD; ISOVECTORS; MEV RANGE; NUCLEON-NUCLEON INTERACTIONS; PERTURBATION THEORY; RANDOM PHASE APPROXIMATION; THREE-BODY PROBLEM

### Citation Formats

```
Papakonstantinou, P., Roth, R., and Paar, N..
```*Nuclear collective excitations using correlated realistic interactions: The role of explicit random-phase approximation correlations*. United States: N. p., 2007.
Web. doi:10.1103/PHYSREVC.75.014310.

```
Papakonstantinou, P., Roth, R., & Paar, N..
```*Nuclear collective excitations using correlated realistic interactions: The role of explicit random-phase approximation correlations*. United States. doi:10.1103/PHYSREVC.75.014310.

```
Papakonstantinou, P., Roth, R., and Paar, N.. Mon .
"Nuclear collective excitations using correlated realistic interactions: The role of explicit random-phase approximation correlations". United States.
doi:10.1103/PHYSREVC.75.014310.
```

```
@article{osti_20990949,
```

title = {Nuclear collective excitations using correlated realistic interactions: The role of explicit random-phase approximation correlations},

author = {Papakonstantinou, P. and Roth, R. and Paar, N.},

abstractNote = {We examine to what extent correlated realistic nucleon-nucleon interactions, derived within the unitary correlation operator method (UCOM), can describe nuclear collective motion in the framework of first-order random-phase approximation (RPA). To this end we employ the correlated Argonne V18 interaction in calculations within the so-called ''Extended'' RPA (ERPA) and investigate the response of closed-shell nuclei. The ERPA is a renormalized RPA version which considers explicitly the depletion of the Fermi sea due to long-range correlations and thus allows us to examine how these affect the excitation spectra. It is found that the effect on the properties of giant resonances is rather small. Compared to the standard RPA, where excitations are built on top of the uncorrelated Hartree-Fock (HF) ground state, their centroid energies decrease by up to 1 MeV, approximately, in the isovector channel. The isoscalar response is less affected in general. Thus, the disagreement between our previous UCOM-based RPA calculations and the experimental data are to be attributed to other effects, namely to residual three-body terms in the Hamiltonian and to higher-order configurations. Single-particle energies and occupation probabilities obtained within the ERPA are compared with corresponding HF and perturbation-theory results and are discussed as well. The ERPA formalism is presented in detail.},

doi = {10.1103/PHYSREVC.75.014310},

journal = {Physical Review. C, Nuclear Physics},

number = 1,

volume = 75,

place = {United States},

year = {Mon Jan 15 00:00:00 EST 2007},

month = {Mon Jan 15 00:00:00 EST 2007}

}