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We present a way for calculating the Lagrangian path integral measure directly from the Hamiltonian Schwinger--Dyson equations. The method agrees with the usual way of deriving the measure, however it may be applied to all theories, even…

High Energy Physics - Theory · Physics 2007-05-23 Aleksandar R. Bogojević , Dragan Popović

We have developed a numerical approach to compute real-time path integral expressions for quantum transport problems out of equilibrium. The scheme is based on a deterministic iterative summation of the path integral (ISPI) for the…

Mesoscale and Nanoscale Physics · Physics 2008-05-16 S. Weiss , J. Eckel , M. Thorwart , R. Egger

In recent years efficient algorithms have been developed for the numerical computation of relativistic single-particle path integrals in quantum field theory. Here, we adapt this "worldline Monte Carlo" approach to the standard problem of…

With the path integral approach, the thermal average in a multi-electronic-state quantum systems can be approximated by the ring polymer representation on an extended configuration space, where the additional degrees of freedom are…

Numerical Analysis · Mathematics 2020-11-24 Xiaoyu Lei , Zhennan Zhou

We present a methodology for accelerating the estimation of the free energy from path integral Monte Carlo simulations by considering an intermediate artificial reference system where interactions are inexpensive to evaluate numerically.…

We present a numerical path-integral iteration scheme for the low dimensional reduced density matrix of a time-dependent quantum dissipative system. Our approach simultaneously accounts for the combined action of a microscopically modelled…

Quantum Physics · Physics 2016-10-12 A. M. Barth , A. Vagov , V. M. Axt

We present full quantum statistical energetics of some electron-light nuclei systems. This is accomplished with the path integral Monte Carlo method. The effects on energetics arising from the change in the nuclear mass are studied. The…

Chemical Physics · Physics 2013-05-30 Ilkka Kylänpää , Tapio T. Rantala , David M. Ceperley

A novel method for simulating the statistical mechanics of molecular systems in which both nuclear and electronic degrees of freedom are treated quantum mechanically is presented. The scheme combines a path integral description of the…

Computational Physics · Physics 2009-10-31 Ruben O. Weht , Jorge Kohanoff , Dario A. Estrin , Charusita Chakravarty

The tunneling decay event of a metastable state in a fully connected quantum spin model can be simulated efficiently by path integral quantum Monte Carlo (QMC) [Isakov $et~al.$, Phys. Rev. Lett. ${\bf 117}$, 180402 (2016).]. This is because…

Quantum Physics · Physics 2017-11-01 Zhang Jiang , Vadim N. Smelyanskiy , Sergio Boixo , Hartmut Neven

Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying…

We have developed a numerically exact approach to compute real-time path integral expressions for quantum transport problems out of equilibrium. The scheme is based on a deterministic iterative summation of the path integral (ISPI) for the…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 S. Weiss , R. Hützen , D. Becker , J. Eckel , R. Egger , M. Thorwart

Full quantum statistical $NVT$ simulation of the five-particle system H$_3^+$ has been carried out using the path integral Monte Carlo method. Structure and energetics is evaluated as a function of temperature up to the thermal dissociation…

Quantum Physics · Physics 2015-05-18 Ilkka Kylänpää , Tapio T. Rantala

This work is devoted to the thermodynamics of high-temperature dense hydrogen plasmas in the pressure region between $10^{-1}$ and $10^2$ Mbar. In particular we present for this region results of extensive calculations based on a recently…

Plasma Physics · Physics 2009-11-07 V. S. Filinov , M. Bonitz , W. Ebeling , V. E. Fortov

The book deals with a stochastic formulation of path integration in real time, by rotating the_space_ variables over exp(i pi/4). Preliminary chapters deal with quantum and classical mechanics, probability theory and stochastic calculus,…

Quantum Physics · Physics 2007-05-23 Alec Maassen van den Brink

In nuclear fusion and fission, fluctuation and dissipation arise due to the coupling of collective degrees of freedom with internal excitations. Close to the barrier, both quantum, statistical and non-Markovian effects are expected to be…

Nuclear Theory · Physics 2010-04-06 G. Hupin , D. Lacroix

The simple method for simulation of ``thermal'' hadron spectra in ultrarelativistic heavy ion collisions including longitudinal, transverse and elliptic flow is developed. The model is realized as fast Monte-Carlo event generator.

High Energy Physics - Phenomenology · Physics 2007-05-23 I. P. Lokhtin , A. M. Snigirev

A path integral method, combined with atomistic spin dynamics simulations, has been developed to calculate thermal quantum expectation values using a classical approach. In this study, we show how to treat Hamiltonians with non-linear…

Quantum Physics · Physics 2024-08-12 Thomas Nussle , Pascal Thibaudeau , Stam Nicolis

The \emph{ab initio} path integral Monte Carlo (PIMC) approach is one of the most successful methods in quantum many-body theory. A particular strength of this method is its straightforward access to imaginary-time correlation functions…

Statistical Mechanics · Physics 2021-08-25 Tobias Dornheim , Zhandos A. Moldabekov , Jan Vorberger

We present fast algorithms for the summation of Dyson series and the inchworm Monte Carlo method for quantum systems that are coupled with harmonic baths. The algorithms are based on evolving the integro-differential equations where the…

Quantum Physics · Physics 2022-06-08 Zhenning Cai , Jianfeng Lu , Siyao Yang

We carry out highly accurate \emph{ab initio} path integral Monte Carlo (PIMC) simulations to directly estimate the free energy of various warm dense matter systems including the uniform electron gas and hydrogen without any nodal…

Quantum Gases · Physics 2024-07-02 Tobias Dornheim , Zhandos Moldabekov , Sebastian Schwalbe , Jan Vorberger
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