We present and implement a parquet approximation within the dual-fermion formalism based on a partial bosonization of the dual vertex function which substantially reduces the computational cost of the calculation. The method relies on splitting the vertex exactly into single-boson exchange contributions and a residual four-fermion vertex, which physically embody, respectively, long- and short-range spatial correlations. After recasting the parquet equations in terms of the residual vertex, these are solved using the truncated-unity method of Eckhardt et al. [Phys. Rev. B 101, 155104 (2020)2469-995010.1103/PhysRevB.101.155104], which allows for a rapid convergence with the number of form factors in different regimes. While our numerical treatment of the parquet equations can be restricted to only a few Matsubara frequencies, reminiscent of Astretsov et al. [Phys. Rev. B 101, 075109 (2020)2469-995010.1103/PhysRevB.101.075109], the one- and two-particle spectral information is fully retained. In applications to the two-dimensional Hubbard model the method agrees quantitatively with a stochastic summation of diagrams over a wide range of parameters.

Boson-exchange parquet solver for dual fermions / Krien, F.; Valli, A.; Chalupa, P.; Capone, M.; Lichtenstein, A. I.; Toschi, A.. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 102:19(2020), pp. 1-17. [10.1103/PhysRevB.102.195131]

Boson-exchange parquet solver for dual fermions

Valli A.;Capone M.;
2020-01-01

Abstract

We present and implement a parquet approximation within the dual-fermion formalism based on a partial bosonization of the dual vertex function which substantially reduces the computational cost of the calculation. The method relies on splitting the vertex exactly into single-boson exchange contributions and a residual four-fermion vertex, which physically embody, respectively, long- and short-range spatial correlations. After recasting the parquet equations in terms of the residual vertex, these are solved using the truncated-unity method of Eckhardt et al. [Phys. Rev. B 101, 155104 (2020)2469-995010.1103/PhysRevB.101.155104], which allows for a rapid convergence with the number of form factors in different regimes. While our numerical treatment of the parquet equations can be restricted to only a few Matsubara frequencies, reminiscent of Astretsov et al. [Phys. Rev. B 101, 075109 (2020)2469-995010.1103/PhysRevB.101.075109], the one- and two-particle spectral information is fully retained. In applications to the two-dimensional Hubbard model the method agrees quantitatively with a stochastic summation of diagrams over a wide range of parameters.
2020
102
19
1
17
195131
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.102.195131
Krien, F.; Valli, A.; Chalupa, P.; Capone, M.; Lichtenstein, A. I.; Toschi, A.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/117493
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