Ground and excited states of even-numbered Hubbard ring at half-filling: comparison of the extended Gutzwiller approach with exact diagonalization

Journal Article · 26 March 2023 · Journal of Physics. Condensed Matter

DOI: https://doi.org/10.1088/1361-648x/acc7ed · OSTI ID:1964136

Fang, Yimei  ^[1]; Zhang, Feng ^[2]; Ye, Zhuo  ^[2]; Zhang, Han  ^[3]; Lu, Wen-Cai  ^[4]; Wu, Shunqing  ^[1]; Yao, Yong-Xin ^[2]; Wang, Cai-Zhuang  ^[5]; Ho, Kai-Ming ^[6]

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1. Xiamen University (China)
2. Ames Laboratory, Ames, IA (United States)
3. Qingdao University (China)
4. Qingdao University, Shandong (China)
5. Ames Laboratory, and Iowa State University, Ames, IA (United States)
6. Iowa State University, Ames, IA (United States)

It remains a great challenge in condensed matter physics to develop a method to treat strongly correlated many-body systems with balanced accuracy and efficiency. We introduce an extended Gutzwiller (EG) method incorporating a manifold technique, which builds an effective manifold of the many-body Hilbert space, to describe the ground- and excited-state properties of strongly correlated electrons. Here we systematically apply an EG projector onto the ground and excited states of a non-interacting system. Diagonalization of the true Hamiltonian within the manifold formed by the resulting EG wavefunctions gives the approximate ground and excited states of the correlated system. To validate this technique, we implement it on even-numbered fermionic Hubbard rings at half-filling with periodic boundary conditions, and compare the results with the exact diagonalization (ED) method. The EG method is capable of generating high-quality ground and low-lying excited state wavefunctions, as evidenced by the high overlaps of wavefunctions between the EG and ED methods. Favorable comparisons are also achieved for other quantities including the total energy, the double occupancy, the total spin and the staggered magnetization. With the capability of accessing the excited states, the EG method can capture the essential features of the one-electron removal spectral function that contains contributions from states deep in the excited spectrum. Finally, we provide an outlook on the application of this method on large extended systems.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; National Natural Science Foundation of China; Central Universities of China
• Grant/Contract Number: AC02-07CH11358
• OSTI ID: 1964136
• Report Number(s): IS-J-11,021
• Journal Information: Journal of Physics. Condensed Matter, Journal Name: Journal of Physics. Condensed Matter Journal Issue: 26 Vol. 35; ISSN 0953-8984
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English