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We present a unified formulation for quantum statistical physics based on the representation of the density matrix as a functional integral. We identify the stochastic variable of the effective statistical theory that we derive as a…

Quantum Physics · Physics 2014-11-18 A. Bessa , C. A. A. de Carvalho , E. S. Fraga

We study the structure of the time evolution of the density matrix in contact with a thermal bath in a standard projection operator sheme. The reduced density matrix of the system in the steady state is obtained by tracing out the degree of…

Statistical Mechanics · Physics 2009-05-04 Takashi Mori , Seiji Miyashita

An extremely fast time-harmonic finite element solver developed for the transmission analysis of photonic crystals was applied to mask simulation problems. The applicability was proven by examining a set of typical problems and by a…

Optics · Physics 2009-05-28 S. Burger , R. Köhle , L. Zschiedrich , W. Gao , F. Schmidt , R. März , C. Nölscher

We present a finite element scheme for fractional diffusion problems with varying diffusivity and fractional order. We consider a symmetric integral form of these nonlocal equations defined on general geometries and in arbitrary bounded…

Numerical Analysis · Mathematics 2023-06-28 Wenyu Lei , George Turkiyyah , Omar Knio

Recent developments in the numerical renormalization group (NRG) allow the construction of the full density matrix (FDM) of quantum impurity models (see A. Weichselbaum and J. von Delft) by using the completeness of the eliminated states…

Strongly Correlated Electrons · Physics 2012-09-04 L. Merker , A. Weichselbaum , T. A. Costi

We present a finite-difference method for the topology optimization of permanent magnets that is based on the FFT accelerated computation of the stray-field. The presented method employs the density approach for topology optimization and…

Computational Physics · Physics 2017-10-11 Claas Abert , Christian Huber , Florian Bruckner , Christoph Vogler , Gregor Wautischer , Dieter Suess

In this work we apply the Lie group representation method introduced in the real time formalism for finite-temperature quantum-field theory, thermofield dynamics, to derive a spinorial density matrix equation. Symmetry properties of such…

High Energy Physics - Theory · Physics 2007-05-23 F. C. Khanna , A. E. Santana , A. Matos Neto , J. D. M. Vianna , T. Kopf

We present a new algorithm to calculate the thermodynamic quantities of three-dimensional (3D) classical statistical systems, based on the ideas of the tensor product state and the density matrix renormalization group. We represent the…

Statistical Mechanics · Physics 2008-12-18 Nobuya Maeshima , Yasuhiro Hieida , Yasuhiro Akutsu , Tomotoshi Nishino , Kouichi Okunishi

We present a Wave Operator Minimization (WOM) method for calculating the Fermi-Dirac density matrix for electronic structure problems at finite temperature while preserving physicality by construction using the wave operator, i.e., the…

Quantum Physics · Physics 2024-04-03 Jacob M. Leamer , William Dawson , Denys I. Bondar

We present a real-space formulation and higher-order finite-difference implementation of periodic Orbital-free Density Functional Theory (OF-DFT). Specifically, utilizing a local reformulation of the electrostatic and kernel terms, we…

Computational Physics · Physics 2015-12-23 Swarnava Ghosh , Phanish Suryanarayana

In this paper we study the thermal effective behaviour for 3D multiphase composite material consisting of three isotropic phases which are the matrix, the inclusions and the coating media. For this purpose we use an accelerated FFT-based…

Computational Engineering, Finance, and Science · Computer Science 2015-04-29 Sophie Lemaitre , Vladimir Salnikov , Daniel Choi , Philippe Karamian

We propose two complimentary numerical methods for rigorous computation of dynamic structure factor at zero temperature. One solution is to solve Schrodinger equation using time dependent variational principle (TDVP) with matrix product…

Strongly Correlated Electrons · Physics 2019-01-24 Ling Wang , Hai-Qing Lin

We introduce a method to carry out zero-temperature calculations within density functional theory (DFT) but without relying on the Born-Oppenheimer (BO) approximation for the ionic motion. Our approach is based on the finite-temperature…

Materials Science · Physics 2018-11-21 Grigory Kolesov , Efthimios Kaxiras , Efstratios Manousakis

Thermoreflectance techniques, including time-domain thermoreflectance (TDTR), frequency-domain thermoreflectance (FDTR), and the square-pulsed source (SPS) method, are powerful tools for characterizing the thermal properties of bulk and…

Applied Physics · Physics 2025-04-04 Tao Chen , Puqing Jiang

The density matrix renormalization group (DMRG) method and its applications to finite temperatures and two-dimensional systems are reviewed. The basic idea of the original DMRG method, which allows precise study of the ground state…

Strongly Correlated Electrons · Physics 2009-11-10 Naokazu Shibata

We describe a Hartree ensemble method to approximately solve the Heisenberg equations for the \phi^4 model in 1+1 dimensions. We compute the energies and number densities of the quantum particles described by the \phi field and find that…

High Energy Physics - Lattice · Physics 2016-09-01 M. Salle , J. Smit , J. C. Vink

We present a time-domain iteration scheme for solving the Dynamical Mean-Field Theory (DMFT) self-consistent equations using retarded Green's functions in real time. Unlike conventional DMFT approaches that operate in imaginary time or…

Strongly Correlated Electrons · Physics 2026-01-28 Chakradhar Rangi , Aadi Singh , Ka-Ming Tam

Landauer's principle gives a fundamental limit to the thermodynamic cost of erasing information. Its saturation requires a reversible isothermal process, and hence infinite time. We develop a finite-time version of Landauer's principle for…

Quantum Physics · Physics 2023-11-08 Alberto Rolandi , Martí Perarnau-Llobet

In this article, an efficient transient electricalthermal co-simulation method based on the finite element method (FEM) and the discontinuous Galerkin time-domain (DGTD) method is developed for electrical-thermal coupling analysis of…

Numerical Analysis · Mathematics 2023-04-06 Kai Zhu , Shunchuan Yang

In the framework of quantum thermodynamics, we propose a method to quantitatively describe thermodynamic quantities for out-of-equilibrium interacting many-body systems. The method is articulated in various approximation protocols which…

Quantum Physics · Physics 2018-02-22 Marcela Herrera , Roberto M. Serra , Irene D'Amico