## This content will become publicly available on October 9, 2020

# Toward scalable many-body calculations for nuclear open quantum systems using the Gamow Shell Model

## Abstract

Drip-line nuclei have very different properties from those of the valley of stability, as they are weakly bound and resonant. Therefore, the models devised for stable nuclei can no longer be applied therein. Hence, a new theoretical tool, the Gamow Shell Model (GSM), has been developed to study the many-body states occurring at the limits of the nuclear chart. GSM is a configuration interaction model based on the use of the so-called Berggren basis, which contains bound, resonant and scattering states, so that inter-nucleon correlations are fully taken into account and the asymptotes of extended many-body wave functions are precisely handled. However, large complex symmetric matrices must be diagonalized in this framework, therefore the use of very powerful parallel machines is needed therein. So, in order to fully take advantage of their power, a 2D partitioning scheme using hybrid MPI/OpenMP parallelization has been developed in our GSM code. The specificities of the 2D partitioning scheme in the GSM framework will be described and illustrated with numerical examples. It will then be shown that the introduction of this scheme in the GSM code greatly enhances its capabilities.

- Authors:

- Michigan State Univ., East Lansing, MI (United States); Peking Univ., Beijing (China); Grand Accélérateur National d’Ions Lourds (GANIL), Caen (France); Chinese Academy of Sciences (CAS), Lanzhou (China)
- Michigan State Univ., East Lansing, MI (United States)
- Inst. of Nuclear Physics PAN, Kraków (Poland); Michigan State Univ., East Lansing, MI (United States). NSCL/FRIB Lab.; Grand Accélérateur National d’Ions Lourds (GANIL), Caen (France

- Publication Date:

- Research Org.:
- Michigan State Univ., East Lansing, MI (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21). Scientific Discovery through Advanced Computing (SciDAC); USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); National Natural Science Foundation of China (NNSFC)

- OSTI Identifier:
- 1571270

- Alternate Identifier(s):
- OSTI ID: 1575939

- Grant/Contract Number:
- SC0018083; SC0013365; SC0008511; 11435014; SC0009971; AC05-00OR22725; AC02-05CH11231

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Computer Physics Communications

- Additional Journal Information:
- Journal Name: Computer Physics Communications; Journal ID: ISSN 0010-4655

- Publisher:
- Elsevier

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Configuration interaction; MPI/openMP hybrid parallelization; 2D partitioning

### Citation Formats

```
Michel, Nicholas, Aktulga, H. M., and Jaganathen, Y. Toward scalable many-body calculations for nuclear open quantum systems using the Gamow Shell Model. United States: N. p., 2019.
Web. doi:10.1016/j.cpc.2019.106978.
```

```
Michel, Nicholas, Aktulga, H. M., & Jaganathen, Y. Toward scalable many-body calculations for nuclear open quantum systems using the Gamow Shell Model. United States. doi:10.1016/j.cpc.2019.106978.
```

```
Michel, Nicholas, Aktulga, H. M., and Jaganathen, Y. Wed .
"Toward scalable many-body calculations for nuclear open quantum systems using the Gamow Shell Model". United States. doi:10.1016/j.cpc.2019.106978.
```

```
@article{osti_1571270,
```

title = {Toward scalable many-body calculations for nuclear open quantum systems using the Gamow Shell Model},

author = {Michel, Nicholas and Aktulga, H. M. and Jaganathen, Y.},

abstractNote = {Drip-line nuclei have very different properties from those of the valley of stability, as they are weakly bound and resonant. Therefore, the models devised for stable nuclei can no longer be applied therein. Hence, a new theoretical tool, the Gamow Shell Model (GSM), has been developed to study the many-body states occurring at the limits of the nuclear chart. GSM is a configuration interaction model based on the use of the so-called Berggren basis, which contains bound, resonant and scattering states, so that inter-nucleon correlations are fully taken into account and the asymptotes of extended many-body wave functions are precisely handled. However, large complex symmetric matrices must be diagonalized in this framework, therefore the use of very powerful parallel machines is needed therein. So, in order to fully take advantage of their power, a 2D partitioning scheme using hybrid MPI/OpenMP parallelization has been developed in our GSM code. The specificities of the 2D partitioning scheme in the GSM framework will be described and illustrated with numerical examples. It will then be shown that the introduction of this scheme in the GSM code greatly enhances its capabilities.},

doi = {10.1016/j.cpc.2019.106978},

journal = {Computer Physics Communications},

number = ,

volume = ,

place = {United States},

year = {2019},

month = {10}

}