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Space-time dependence of imaginary-time propagators, vital for \textit{ab initio} and many-body calculations based on quantum field theories, has been revealed to be compressible using Quantum Tensor Trains (QTTs) [Phys. Rev. X {\bf 13},…

Strongly Correlated Electrons · Physics 2025-01-09 Haruto Takahashi , Rihito Sakurai , Hiroshi Shinaoka

We demonstrate that a machine learning framework based on kernel ridge regression can encode and predict the self-energy of one-dimensional Hubbard models using only mean-field features such as static and dynamic Hartree-Fock quantities and…

Strongly Correlated Electrons · Physics 2026-05-08 Mateo Cárdenes Wuttig

The open-source library, irbasis, provides easy-to-use tools for two sets of orthogonal functions named intermediate representation (IR). The IR basis enables a compact representation of the Matsubara Green's function and efficient…

Computational Physics · Physics 2019-06-28 Naoya Chikano , Kazuyoshi Yoshimi , Junya Otsuki , Hiroshi Shinaoka

We present a numerically stable Quantum Monte Carlo algorithm to calculate zero-temperature imaginary-time Green functions $ G(\vec{r}, \tau) $ for Hubbard type models. We illustrate the efficiency of the algorithm by calculating the…

Condensed Matter · Physics 2009-10-28 F. F. Assaad , M. Imada

We formulate an efficient scheme to perform Migdal-Eliashberg calculation considering the retardation effect from first principles. While the conventional approach requires a huge number of Matsubara frequencies, we show that the…

The ill-posed analytic continuation problem for Green's functions or self-energies can be done using the Pad\'e rational polynomial approximation. However, to extract accurate results from this approximation, high precision input data of…

Strongly Correlated Electrons · Physics 2017-06-28 Xing-Jie Han , Hai-Jun Liao , Hai-Dong Xie , Rui-Zhen Huang , Zi Yang Meng , Tao Xiang

Inspired by the recent proposed Legendre orthogonal polynomial representation of imaginary-time Green's functions, we develop an alternate representation for the Green's functions of quantum impurity models and combine it with the…

Strongly Correlated Electrons · Physics 2016-12-08 Li Huang , Liang Du

The interaction of electrons with quantized phonons and photons underlies the ultrafast dynamics of systems ranging from molecules to solids, and it gives rise to a plethora of physical phenomena experimentally accessible using…

Strongly Correlated Electrons · Physics 2021-07-21 Daniel Karlsson , Robert van Leeuwen , Yaroslav Pavlyukh , Enrico Perfetto , Gianluca Stefanucci

We present results for many-body perturbation theory for the one-body Green's function at finite temperatures using the Matsubara formalism. Our method relies on the accurate representation of the single-particle states in standard Gaussian…

Strongly Correlated Electrons · Physics 2018-04-04 Michael Schüler , Yaroslav Pavlyukh

We use a diagrammatic hopping expansion to calculate finite-temperature Green functions of the Bose-Hubbard model which describes bosons in an optical lattice. This technique allows for a summation of subsets of diagrams, so the divergence…

Statistical Mechanics · Physics 2013-05-30 Matthias Ohliger , Axel Pelster

We exploit the many-body self-consistent Green's function method to analyze finite-temperature properties of infinite nuclear matter and to explore the behavior of the thermal index used to simulate thermal effects in equations of state for…

Nuclear Theory · Physics 2019-08-23 Arianna Carbone , Achim Schwenk

We investigate the possibility to assist the numerically ill-posed calculation of spectral properties of interacting quantum systems in thermal equilibrium by extending the imaginary-time simulation to a finite Schwinger-Keldysh contour.…

Strongly Correlated Electrons · Physics 2013-02-25 Andreas Dirks , Martin Eckstein , Thomas Pruschke , Philipp Werner

Grid independent is associated with the accuracy or even rationality of numerical results. This paper takes two-dimensional steady heat transfer for example to reveal the effect of grid resolution on numerical results. The law of grid…

Mathematical Physics · Physics 2007-05-23 Yao Wei , Wang Jian , Liao Guangxuan

Many-electron systems at substantial finite temperatures and densities present a major challenge to density functional theory. Very little is known about the free-energy behavior over the temperature range of interest, for example, in the…

Materials Science · Physics 2012-01-25 Travis Sjostrom , Frank E. Harris , S. B. Trickey

We illustrate how to calculate the finite-temperature linear-response conductance of quantum impurity models from the Matsubara Green function. A continued fraction expansion of the Fermi distribution is employed which was recently…

Strongly Correlated Electrons · Physics 2015-05-19 C. Karrasch , V. Meden , K. Schönhammer

We propose an optimal operation control strategy for an electro-thermal microgrid. Compared to existing work, our approach increases flexibility by operating the thermal network with variable flow temperatures and in that way explicitly…

Systems and Control · Electrical Eng. & Systems 2024-04-03 Max Rose , Christian A. Hans , Johannes Schiffer

We revise critically existing approaches to evaluation of thermodynamic potentials within the Green's function calculations at finite electronic temperatures. We focus on the entropy and show that usual technical problems related to the…

Materials Science · Physics 2018-02-26 Ilja Turek , Josef Kudrnovsky , Vaclav Drchal

A new computational method for finite-temperature properties of strongly correlated electrons is proposed by extending the variational Monte Carlo method originally developed for the ground state. The method is based on the path integral in…

Strongly Correlated Electrons · Physics 2016-06-10 Kensaku Takai , Kota Ido , Takahiro Misawa , Youhei Yamaji , Masatoshi Imada

An algorithm is presented to calculate the electronic local time-dependent Green's operator for manganites-related hamiltonians. This algorithm is proved to scale with the number of states $N$ in the Hilbert-space to the 1.55 power, is able…

Strongly Correlated Electrons · Physics 2009-11-10 H. Aliaga

We implement a highly efficient strong-coupling expansion for the Green's function of the Hubbard model. In the limit of extreme correlations, where the onsite interaction is infinite, the evaluation of diagrams simplifies dramatically…

Strongly Correlated Electrons · Physics 2014-06-06 Ehsan Khatami , Edward Perepelitsky , Marcos Rigol , B. Sriram Shastry