This paper constructs a general method for obtaining series expansions of the logarithm of the configuration function $F$ . For an $N$ -body quantum system with Hamiltonian $H$ and inverse temperature $\ensuremath{\beta}$, the configuration function is the ratio of the exact to the free coordinate-space heat kernels: $F=\frac{〈\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}|{e}^{\ensuremath{-}\ensuremath{\beta}H}|{\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}}^{\ensuremath{'}}〉}{〈\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}|{e}^{\ensuremath{-}\ensuremath{\beta}{H}_{0}}|{\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}}^{\ensuremath{'}}〉}$. Expansion of $\mathrm{ln}F$ in Planck's constant $h$ leads to the semiclassical expansion of Wigner and Kirkwood, whereas the series in the variable $\ensuremath{\beta}$ provides the high-temperature expansion. By the introduction of an appropriate linked-graph method, it is shown how to obtain explicit formulas for the coefficient functions that enter either of these two series. Further, it is established that the same results can be derived by using the Feynman-Kac path-integral description of the partition function.This paper constructs a general method for obtaining series expansions of the logarithm of the configuration function $F$. For an $N$-body quantum system with Hamiltonian $H$ and inverse temperature $\ensuremath{\beta}$, the configuration function is the ratio of the exact to the free coordinate-space heat kernels: $F=\frac{〈\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}|{e}^{\ensuremath{-}\ensuremath{\beta}H}|{\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}}^{\ensuremath{'}}〉}{〈\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}|{e}^{\ensuremath{-}\ensuremath{\beta}{H}_{0}}|{\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}}^{\ensuremath{'}}〉}$. Expansion of $\mathrm{ln}F$ in Planck's constant $h$ leads to the semiclassical expansion of Wigner and Kirkwood, whereas the series in the variable $\ensuremath{\beta}$ provides the high-temperature expansion. By the introduction of an appropriate linked-graph method, it is shown how to obtain explicit formulas for the coefficient functions that enter either of these two series. Further, it is established that the same results can be derived by using the Feynman-Kac path-integral description of the partition function.

Physical Review AJan 1, 1982100 citations

Lectures on correlation functions

Alexander L. Fetter

Lecture notes in physicsJan 1, 19832 citations

2n-point renormalized coupling constants in the three-dimensional Ising model:Estimates by high temperature series to order Β17

P. Butera, M. Comi

We compute the 2n-point renormalized coupling constants in the symmetric phase of the three-dimensional (3D) Ising model on the simple cubic lattice in terms of the high temperature expansions O(${\mathrm{\ensuremath{\mathrm{B}}}}^{17}$) of the Fourier transformed 2n-point connected correlation functions at zero momentum. Our high temperature estimates of these quantities, which enter into the small field expansion of the effective potential for a 3D scalar field at the infrared fixed point or, equivalently, in the critical equation of state of the 3D Ising model universality class, are compared with recent results obtained by renormalization group methods, strong coupling, stochastic simulations, as well as previous high temperature expansions.We compute the 2n-point renormalized coupling constants in the symmetric phase of the three-dimensional (3D) Ising model on the simple cubic lattice in terms of the high temperature expansions O(${\mathrm{\ensuremath{\mathrm{B}}}}^{17}$) of the Fourier transformed 2n-point connected correlation functions at zero momentum. Our high temperature estimates of these quantities, which enter into the small field expansion of the effective potential for a 3D scalar field at the infrared fixed point or, equivalently, in the critical equation of state of the 3D Ising model universality class, are compared with recent results obtained by renormalization group methods, strong coupling, stochastic simulations, as well as previous high temperature expansions.

arXiv:hep-lat/9703017Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topicsJun 1, 199740 citations

Fourier–Matsubara series expansion for imaginary–time correlation functions

Panagiotis B. Tolias, Fotios Kalkavouras, Tobias Dornheim

A Fourier-Matsubara series expansion is derived for imaginary-time correlation functions that constitutes the imaginary-time generalization of the infinite Matsubara series for equal-time correlation functions. The expansion is consistent with all known exact properties of imaginary-time correlation functions and opens up new avenues for the utilization of quantum Monte Carlo simulation data. Moreover, the expansion drastically simplifies the computation of imaginary-time density-density correlation functions with the finite temperature version of the self-consistent dielectric formalism. Its existence underscores the utility of imaginary-time as a complementary domain for many-body physics.A Fourier-Matsubara series expansion is derived for imaginary-time correlation functions that constitutes the imaginary-time generalization of the infinite Matsubara series for equal-time correlation functions. The expansion is consistent with all known exact properties of imaginary-time correlation functions and opens up new avenues for the utilization of quantum Monte Carlo simulation data. Moreover, the expansion drastically simplifies the computation of imaginary-time density-density correlation functions with the finite temperature version of the self-consistent dielectric formalism. Its existence underscores the utility of imaginary-time as a complementary domain for many-body physics.

arXiv:2404.01838The Journal of Chemical PhysicsMay 8, 202416 citations

Dressing equations for correlation functions

V. E. Korepin

Journal of Mathematical SciencesNov 1, 19860 citations

This paper constructs a general method for obtaining series expansions of the logarithm of the configuration function

F

. For an

N

-body quantum system with Hamiltonian

H

and inverse temperature $\ensuremath{\beta}$, the configuration function is the ratio of the exact to the free coordinate-space heat kernels: $F=\frac{〈\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}|{e}^{\ensuremath{-}\ensuremath{\beta}H}|{\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}}^{\ensuremath{'}}〉}{〈\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}|{e}^{\ensuremath{-}\ensuremath{\beta}{H}_{0}}|{\stackrel{\ensuremath{\rightarrow}}{\mathrm{x}}}^{\ensuremath{'}}〉}$. Expansion of

\mathrm{ln}F

in Planck's constant

h

leads to the semiclassical expansion of Wigner and Kirkwood, whereas the series in the variable $\ensuremath{\beta}$ provides the high-temperature expansion. By the introduction of an appropriate linked-graph method, it is shown how to obtain explicit formulas for the coefficient functions that enter either of these two series. Further, it is established that the same results can be derived by using the Feynman-Kac path-integral description of the partition function.