ab initio description of open-shell nuclei: merging in...
TRANSCRIPT
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Ab Initio Description of Open-Shell Nuclei: Merging In-Medium SRG and No-Core Shell Model
E. Gebrerufael1 K. Vobig1 H. Hergert2 R. Roth1
1 Institut für Kernphysik, TU Darmstadt 2 NSCL/FRIB Laboratory and Department of Physics & Astronomy, MSU
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 1
12C
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Motivation Why should we merge IM-SRG and NCSM?
NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 2
- limited to light nuclei
- factorial growth of model space
- computationally demanding
- difficult to obtain model-space
convergence
![Page 3: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/3.jpg)
Motivation Why should we merge IM-SRG and NCSM?
+ easy access to heavy nuclei
+ soft computational scaling with A
+ computationally very efficient
+ decoupling in A-body space
IM- NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 2
- limited to light nuclei
- factorial growth of model space
- computationally demanding
- difficult to obtain model-space
convergence
SRG
![Page 4: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/4.jpg)
Motivation Why should we merge IM-SRG and NCSM?
+ easy access to heavy nuclei
+ soft computational scaling with A
+ computationally very efficient
+ decoupling in A-body space
IM- NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 2
- limited to light nuclei
- factorial growth of model space
- computationally demanding
- difficult to obtain model-space
convergence
SRG
- not exact method
- only for ground state
- spectroscopy not straight forward
- currently limited to even nuclei
![Page 5: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/5.jpg)
Motivation Why should we merge IM-SRG and NCSM?
+ easy access to heavy nuclei
+ soft computational scaling with A
+ computationally very efficient
+ decoupling in A-body space
IM- NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 2
- limited to light nuclei
- factorial growth of model space
- computationally demanding
- difficult to obtain model-space
convergence
SRG
- not exact method
- only for ground state
- spectroscopy not straight forward
- currently limited to even nuclei
+ exact method
+ easy access to excited states
+ spectroscopy for free
+ no limitation to even nuclei
![Page 6: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/6.jpg)
Motivation Why should we merge IM-SRG and NCSM?
+ easy access to heavy nuclei
+ soft computational scaling with A
+ computationally very efficient
+ decoupling in A-body space
IM- NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 2
- limited to light nuclei
- factorial growth of model space
- computationally demanding
- difficult to obtain model-space
convergence
- not exact method
- only for ground state
- spectroscopy not straight forward
- currently limited to even nuclei
+ exact method
+ easy access to excited states
+ spectroscopy for free
+ no limitation to even nuclei
![Page 7: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/7.jpg)
Overview
No-Core Shell Model (NCSM)
In-Medium Similarity Renormalization Group (IM-SRG)
Novel Approach: IM-NCSM
Results
o Evolution of Ground-State Energy
o Evolution of Excitation Energies
o Spectra
Summary and Outlook
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 3
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No-Core Shell Model Basics
construct matrix representation of Hamiltonian using basis of HO/HF Slater determinants truncated w.r.t. excitation quanta Nmax
solve large-scale eigenvalue problem for a few smallest eigenvalues
… is one of the most powerful exact ab initio methods
for the p- and lower sd-shell
Barrett, Vary, Navratil, ...
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 4
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No-Core Shell Model Basics
construct matrix representation of Hamiltonian using basis of HO/HF Slater determinants truncated w.r.t. excitation quanta Nmax
solve large-scale eigenvalue problem for a few smallest eigenvalues
range of applicability limited by factorial growth of basis with Nmax & A
adaptive importance-truncation extends the range of NCSM by
reducing the model space to physically relevant states
… is one of the most powerful exact ab initio methods
for the p- and lower sd-shell
Barrett, Vary, Navratil, ...
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 4
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In-Medium Similarity Renormalization Group Basics
flow equation for Hamiltonian:
… uses flow equation for normal-ordered Hamiltonian to decouple
the reference state from its excitations
Tsukiyama, Bogner, Schwenk, Hergert,..
Eskendr Gebrerufael - TU Darmstadt - March 2016 5
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In-Medium Similarity Renormalization Group Basics
flow equation for Hamiltonian:
… uses flow equation for normal-ordered Hamiltonian to decouple
the reference state from its excitations
Tsukiyama, Bogner, Schwenk, Hergert,..
flow parameter
Eskendr Gebrerufael - TU Darmstadt - March 2016 5
generator designed to decouple the reference state
![Page 12: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/12.jpg)
In-Medium Similarity Renormalization Group Basics
flow equation for Hamiltonian:
… uses flow equation for normal-ordered Hamiltonian to decouple
the reference state from its excitations
H in multi-reference normal-ordered form w.r.t. [Kutzelnigg,Mukherjee]
Tsukiyama, Bogner, Schwenk, Hergert,..
flow parameter
Eskendr Gebrerufael - TU Darmstadt - March 2016 5
generator designed to decouple the reference state
![Page 13: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/13.jpg)
In-Medium Similarity Renormalization Group Basics
flow equation for Hamiltonian:
… uses flow equation for normal-ordered Hamiltonian to decouple
the reference state from its excitations
H in multi-reference normal-ordered form w.r.t. [Kutzelnigg,Mukherjee]
Tsukiyama, Bogner, Schwenk, Hergert,..
flow parameter
Eskendr Gebrerufael - TU Darmstadt - March 2016 5
generator designed to decouple the reference state
![Page 14: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/14.jpg)
In-Medium Similarity Renormalization Group Basics
flow equation for Hamiltonian:
… uses flow equation for normal-ordered Hamiltonian to decouple
the reference state from its excitations
H in multi-reference normal-ordered form w.r.t. [Kutzelnigg,Mukherjee]
Tsukiyama, Bogner, Schwenk, Hergert,..
flow parameter
Eskendr Gebrerufael - TU Darmstadt - March 2016 5
generator designed to decouple the reference state
![Page 15: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/15.jpg)
In-Medium Similarity Renormalization Group Basics
flow equation for Hamiltonian:
… uses flow equation for normal-ordered Hamiltonian to decouple
the reference state from its excitations
H in multi-reference normal-ordered form w.r.t. [Kutzelnigg,Mukherjee]
Tsukiyama, Bogner, Schwenk, Hergert,..
flow parameter
Eskendr Gebrerufael - TU Darmstadt - March 2016 5
generator designed to decouple the reference state
![Page 16: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/16.jpg)
Novel Approach: IM-NCSM How should we merge…
NCSM define
reference state
IM-SRG evolve
operators
NCSM extract
observables
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 6
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diagonalize Hamiltonian in small model space
ground state defines reference state
Novel Approach: IM-NCSM How should we merge…
NCSM define
reference state
IM-SRG evolve
operators
NCSM extract
observables
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 6
![Page 18: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/18.jpg)
diagonalize Hamiltonian in small model space
ground state defines reference state
Novel Approach: IM-NCSM How should we merge…
evolve Hamiltonian and other operators
pre-diagonalization in A-body space
NCSM define
reference state
IM-SRG evolve
operators
NCSM extract
observables
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 6
![Page 19: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/19.jpg)
diagonalize Hamiltonian in small model space
ground state defines reference state
Novel Approach: IM-NCSM How should we merge…
evolve Hamiltonian and other operators
pre-diagonalization in A-body space
NCSM define
reference state
IM-SRG evolve
operators
NCSM extract
observables
diagonalize IM-SRG evolved Hamiltonian
obtain eigenstates and extract observables
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 6
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Nmax=0 Slater determinants
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 21: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/21.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 22: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/22.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 23: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/23.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 24: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/24.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 25: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/25.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 26: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/26.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 27: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/27.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 28: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/28.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 29: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/29.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 30: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/30.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 31: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/31.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 32: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/32.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 33: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/33.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 34: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/34.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
for sufficiently large flow parameter eigenvalues in Nmax=0, 2 and 4 equal
Nmax=0 eigenstates Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
![Page 35: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/35.jpg)
Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
for sufficiently large flow parameter eigenvalues in Nmax=0, 2 and 4 equal
Nmax=0 eigenstates Slater determinants
IM-SRG decouples reference state from Nmax =2 and 4 spaces
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
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Novel Approach: IM-NCSM Hamiltonian Matrix in A-Body Basis: 12C
for sufficiently large flow parameter eigenvalues in Nmax=0, 2 and 4 equal
Nmax=0 eigenstates Slater determinants
IM-SRG decouples reference state from Nmax =2 and 4 spaces
Why do E(s) and Nmax=0 eigenvalue differ?
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 7
Nmax=2 Nmax=4
Nm
ax=4
N
max
=2
Nm
ax=0
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 states couple to
reference state
first basis state = reference state
Nmax=0 eigenstates
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 8
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 states couple to
reference state
first basis state = reference state
Nmax=0 eigenstates
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 8
![Page 39: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/39.jpg)
Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 states couple to
reference state
E(s) and Nmax=0 eigenvalue
cannot be identical
first basis state = reference state
Nmax=0 eigenstates
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 8
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 states couple to
reference state
E(s) and Nmax=0 eigenvalue
cannot be identical
diagonalization of evolved Hamiltonian
necessary
first basis state = reference state
Nmax=0 eigenstates
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 8
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Overview
No-Core Shell Model (NCSM)
In-Medium Similarity Renormalization Group (IM-SRG)
Novel Approach: IM-NCSM
Results
o Evolution of Ground-State Energy
o Evolution of Excitation Energies
o Spectra
Summary and Outlook
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 9
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Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
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Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
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Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
drastically enhanced model-space convergence for IM-NCSM
![Page 45: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/45.jpg)
Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
drastically enhanced model-space convergence for IM-NCSM
![Page 46: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/46.jpg)
Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
drastically enhanced model-space convergence for IM-NCSM
NCSM with explicit 3N
![Page 47: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/47.jpg)
Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
drastically enhanced model-space convergence for IM-NCSM
NO2B approximation + induced many-body contribution = 4.0 MeV (≈ 5 %)
NCSM with explicit 3N
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Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
drastically enhanced model-space convergence for IM-NCSM
NO2B approximation + induced many-body contribution = 4.0 MeV (≈ 5 %)
for s > 0.3 MeV-1 induced many-body contribution becomes significant
NCSM with explicit 3N
![Page 49: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/49.jpg)
Results Evolution of Ground-State Energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 10
drastically enhanced model-space convergence for IM-NCSM
NO2B approximation + induced many-body contribution = 4.0 MeV (≈ 5 %)
for s > 0.3 MeV-1 induced many-body contribution becomes significant
NCSM with explicit 3N
![Page 50: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/50.jpg)
Results Evolution of Ground-State Energy
E(s) more robust than in 12C case
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 11
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Results Evolution of Ground-State Energy
E(s) more robust than in 12C case
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 11
NCSM with explicit 3N
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Results Evolution of Ground-State Energy
E(s) more robust than in 12C case
NO2B approximation + induced many-body contribution = 2.3 MeV (< 2 %)
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 11
NCSM with explicit 3N
![Page 53: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/53.jpg)
Results Evolution of Ground-State Energy
E(s) more robust than in 12C case
NO2B approximation + induced many-body contribution = 2.3 MeV (< 2 %)
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 11
NCSM with explicit 3N
![Page 54: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/54.jpg)
Results Evolution of Excitation Energies
E* of 2+ increases abruptly at the end due to kink in ground-state energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 12
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Results Evolution of Excitation Energies
E* of 2+ increases abruptly at the end due to kink in ground-state energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 12
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Results Evolution of Excitation Energies
E* of 2+ increases abruptly at the end due to kink in ground-state energy
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 12
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Results Evolution of Excitation Energies
E* of 2+ increases abruptly at the end due to kink in ground-state energy
E* converges monotonically from above w.r.t. Nmax for evolved Hamiltonian
variational principle valid for E* since ground-state energy converged
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 12
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Results Evolution of Excitation Energies
E* of 2+ increases abruptly at the end due to kink in ground-state energy
E* converges monotonically from above w.r.t. Nmax for evolved Hamiltonian
variational principle valid for E* since ground-state energy converged
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 12
![Page 59: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/59.jpg)
Results Evolution of Excitation Energies
E* of 2+ increases abruptly at the end due to kink in ground-state energy
E* converges monotonically from above w.r.t. Nmax for evolved Hamiltonian
variational principle valid for E* since ground-state energy converged
first excited 0 + very sensitive to flow parameter Hoyle state? Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 12
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Results Evolution of Excitation Energies
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 13
large dependence on s in Nmax=0
dependence on s reduces with increasing Nmax
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Results Evolution of Excitation Energies
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 13
large dependence on s in Nmax=0
dependence on s reduces with increasing Nmax
E* converges monotonically from above for evolved Hamiltonian
![Page 62: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/62.jpg)
Results Evolution of Excitation Energies
analyze E* as function of Nmax
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 13
large dependence on s in Nmax=0
dependence on s reduces with increasing Nmax
E* converges monotonically from above for evolved Hamiltonian
![Page 63: Ab Initio Description of Open-Shell Nuclei: Merging In ...crunch.ikp.physik.tu-darmstadt.de/tnp/pres/2016_msu_gebrerufael.pdf · Ab Initio Description of Open-Shell Nuclei: Merging](https://reader033.vdocuments.site/reader033/viewer/2022042111/5e8ca788e4dec602fe3c9de0/html5/thumbnails/63.jpg)
Results Spectra
IM-NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 14
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Results Spectra
IM-NCSM
uncertainty band due to flow-parameter variation between smax/2 and smax
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 14
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Results Spectra
NCSM IM-NCSM
uncertainty band due to flow-parameter variation between smax/2 and smax
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 14
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Results Spectra
NCSM IM-NCSM
uncertainty band due to flow-parameter variation between smax/2 and smax
2+ and 1+ in IM-NCSM and NCSM in good agreement
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 14
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Results Spectra
NCSM IM-NCSM
uncertainty band due to flow-parameter variation between smax/2 and smax
2+ and 1+ in IM-NCSM and NCSM in good agreement
second 0+ in IM-NCSM closer to experiment (Hoyle?)
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 14
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Results Spectra
NCSM IM-NCSM
uncertainty band due to flow-parameter variation between smax/2 and smax
2+ and 1+ in IM-NCSM and NCSM in good agreement
second 0+ in IM-NCSM closer to experiment (Hoyle?)
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 14
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Results Spectra
first 2+ and 4+ robust and well converged in IM-NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 15
NCSM IM-NCSM
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Results Spectra
first 2+ and 4+ robust and well converged in IM-NCSM
higher-lying states show small flow-parameter dependence
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 15
NCSM IM-NCSM
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Results Spectra
first 2+ and 4+ robust and well converged in IM-NCSM
higher-lying states show small flow-parameter dependence
1+ not yet observed experimentally theoretical prediction
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 15
NCSM IM-NCSM
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Results Spectra
first 2+ and 4+ robust and well converged in IM-NCSM
higher-lying states show small flow-parameter dependence
1+ not yet observed experimentally theoretical prediction
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 15
NCSM IM-NCSM
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Summary
introduced new many-body technique IM-NCSM = IM-SRG + NCSM
exploits the advantages of both approaches
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 16
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Summary
introduced new many-body technique IM-NCSM = IM-SRG + NCSM
exploits the advantages of both approaches
IM-SRG decouples reference state from higher Nmax
extremely enhanced Nmax convergence for subsequent NCSM
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 16
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Summary
introduced new many-body technique IM-NCSM = IM-SRG + NCSM
exploits the advantages of both approaches
IM-SRG decouples reference state from higher Nmax
extremely enhanced Nmax convergence for subsequent NCSM
Nmax≤4 sufficient to extract converged ground-state energies
variational principle becomes valid for excitation energies
since ground-state energy converged
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 16
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Outlook
o variation of several parameters: generator,
o consistent evolution radius, electromagnetic, … operators
o detailed analysis of the Hoyle state in 12C
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 17
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Outlook
o variation of several parameters: generator,
o consistent evolution radius, electromagnetic, … operators
o detailed analysis of the Hoyle state in 12C
o extend applicability of IM-NCSM to odd nuclei
using particle-attached particle-removed formalism
o include three-body operators in IM-SRG
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 17
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Thanks to my group & collaborator • S. Alexa, S. Dentinger, T. Hüther, L. Kreher,
L. Mertes, S. Ruppert, R. Roth, S. Schulz,
H. Spiess, H. Spielvogel, C. Stumpf, A. Tichai,
R. Trippel, K. Vobig, R. Wirth
Institut für Kernphysik, TU Darmstadt
• H. Hergert
NSCL/FRIB, Michigan State University
Thank You For Your Attention
JURECA LOEWE-CSC LICHTENBERG
COMPUTING TIME
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 18
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Appendix
Appendix
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Results NCSM vs. IM-NCSM vs. MR-IM-SRG
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 20
NCSM @ Nmax extrap. IM-NCSM @ Nmax=4 MR-IM-SRG (HFB, White) Experiment
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Results Dependence on Single-Particle Basis
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 21
For small flow parameter Nmax convergence slow in HF basis
induced many-body in HF 4 MeV and in HO < 1 MeV
NCSM with 3N
HF
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Results Dependence on Single-Particle Basis
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 21
For small flow parameter Nmax convergence slow in HF basis
induced many-body in HF 4 MeV and in HO < 1 MeV
NCSM with 3N
Nmax-Extrapolation at s=0
HO
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Results Dependence on
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 22
quite insensitive on
E(s) equal to eigenvalue obtained in for small flow parameter s
since the reference state is an eigenstate obtained in model space
HF
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Results Dependence on
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 22
quite insensitive on
E(s) equal to eigenvalue obtained in for small flow parameter s
since the reference state is an eigenstate obtained in model space
HF
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Results Dependence on
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 23
quite insensitive on
E(s) equal to eigenvalue obtained in for small flow parameter s
since the reference state is an eigenstate obtained in model space
HO
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Results Dependence on
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 23
quite insensitive on
E(s) equal to eigenvalue obtained in for small flow parameter s
since the reference state is an eigenstate obtained in model space
HO
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Results Dependence on
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 23
quite insensitive on
E(s) equal to eigenvalue obtained in for small flow parameter s
since the reference state is an eigenstate obtained in model space
HO
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Results Spectra
excellent agreement between IM-NCSM and NCSM
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NCSM IM-NCSM
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Results Spectra
4+ simply not calculated in NCSM
first excited 0+ shows same behaviour as in 12C
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 25
NCSM IM-NCSM
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Results IM-NCSM: Particle-Attached Particle-Removed Form.
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 26
7 8
6
parent
eigenvalues for small flow parameter independent on parent nucleus
eigenvalues for large flow paremter show dependence on parent nucleus
deviation at the level of 4 MeV (< 4%)
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Results IM-NCSM: Particle-Attached Particle-Removed Form.
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 27
parent
7 8
6
deviation at the level of 5 MeV (< 5%)
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Results IM-NCSM: Particle-Attached Particle-Removed Form.
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 28
7 8
6
parent
deviation at the level of 5 MeV (< 5%)
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Results Evolution of Excitation Energies – On Absolute Scale
2+ perfectly converged on absolute scale
induced many-body contribution different for each state
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Slater det.
Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 16O
E(s) converges monotonically against Nmax=2 eigenvalue
Nmax=2 Slater determinants
IM-SRG decouples reference state
from Nmax =2 space
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 30
Nmax=0
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Slater det.
Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 16O
E(s) converges monotonically against Nmax=2 eigenvalue
Nmax=2 Slater determinants
IM-SRG decouples reference state
from Nmax =2 space
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 30
Nmax=0
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Slater det.
Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 16O
E(s) converges monotonically against Nmax=2 eigenvalue
Nmax=2 Slater determinants
IM-SRG decouples reference state
from Nmax =2 space
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 30
Nmax=0
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Slater det.
Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 16O
E(s) converges monotonically against Nmax=2 eigenvalue
Nmax=2 Slater determinants
IM-SRG decouples reference state
from Nmax =2 space
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 30
Nmax=0
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Nmax=0 Slater determinants
Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 31
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
Eskendr Gebrerufael - TU Darmstadt - Oct. 2016 31
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
for sufficient large flow parameter eigenvalues in Nmax=0 and Nmax=2 equal
Nmax=0 eigenstates
Nmax=2 Slater determinants
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
for sufficient large flow parameter eigenvalues in Nmax=0 and Nmax=2 equal
Nmax=0 eigenstates
Nmax=2 Slater determinants
IM-SRG decouples reference state (not only)
from Nmax =2 space
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Novel Approach: IM-NCSM Hamilton Matrix in A-Body Basis: 12C
for sufficient large flow parameter eigenvalues in Nmax=0 and Nmax=2 equal
Nmax=0 eigenstates
Nmax=2 Slater determinants
IM-SRG decouples reference state (not only)
from Nmax =2 space
-> why do E(s) and Nmax=0 eigenvalue differ?
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free-space SRG
NC
SM
normal ordering
IM-SRG NCSM
IM-NCSM Procedure
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free-space SRG
NC
SM
normal ordering
IM-SRG NCSM
IM-NCSM Procedure
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free-space SRG
NC
SM
normal ordering
IM-SRG NCSM
IM-NCSM Procedure
IM-SRG to get rid of spurious states:
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free-space SRG
NC
SM
normal ordering
IM-SRG
CI
NCSM
IM-NCSM Procedure
IM-SRG to get rid of spurious states:
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IM-NCSM Current Implementation of Imaginary Time
natural orbitals: ni occupation number
… missing terms contain irreducible density matrix
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