0000000000418906

AUTHOR

Florian R. Krajewski

showing 3 related works from this author

Comparison of two non-primitive methods for path integral simulations: Higher-order corrections vs. an effective propagator approach

2002

Two methods are compared that are used in path integral simulations. Both methods aim to achieve faster convergence to the quantum limit than the so-called primitive algorithm (PA). One method, originally proposed by Takahashi and Imada, is based on a higher-order approximation (HOA) of the quantum mechanical density operator. The other method is based upon an effective propagator (EPr). This propagator is constructed such that it produces correctly one and two-particle imaginary time correlation functions in the limit of small densities even for finite Trotter numbers P. We discuss the conceptual differences between both methods and compare the convergence rate of both approaches. While th…

PhysicsOperator (physics)Mathematical analysisCondensed Matter (cond-mat)Order (ring theory)PropagatorEstimatorFOS: Physical sciencesCondensed MatterRate of convergenceQuantum mechanicsPath integral formulationVirial expansionLimit (mathematics)
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Quantum Creep and Quantum-Creep Transitions in 1D Sine-Gordon Chains

2003

Discrete sine-Gordon (SG) chains are studied with path-integral molecular dynamics. Chains commensurate with the substrate show the transition from collective quantum creep to pinning at bead masses slightly larger than those predicted from the continuous SG model. Within the creep regime, a field-driven transition from creep to complete depinning is identified. The effects of disorder in the external potential on the chain's dynamics depend on the potential's roughness exponent $H$, i.e., quantum and classical fluctuations affect the current self-correlation functions differently for $H = 1/2$.

PhysicsCondensed Matter - Materials ScienceStatistical Mechanics (cond-mat.stat-mech)Condensed matter physicsMaterials Science (cond-mat.mtrl-sci)FOS: Physical sciencesGeneral Physics and AstronomyThermal fluctuations02 engineering and technologySubstrate (electronics)021001 nanoscience & nanotechnology01 natural sciencesMolecular dynamicsCreepChain (algebraic topology)Condensed Matter::Superconductivity0103 physical sciencesSine010306 general physics0210 nano-technologyQuantumCondensed Matter - Statistical MechanicsQuantum fluctuationPhysical Review Letters
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Many-body quantum dynamics by adiabatic path-integral molecular dynamics: Disordered Frenkel Kontorova models

2005

The spectral density of quantum mechanical Frenkel Kontorova chains moving in disordered, external potentials is investigated by means of path-integral molecular dynamics. If the second moment of the embedding potential is well defined (roughness exponent ), there is one regime in which the chain is pinned (large masses of chain particles) and one in which it is unpinned (small ). If the embedding potential can be classified as a random walk on large length scales ( ), then the chain is always pinned irrespective of the value of . For , two phonon-like branches appear in the spectra.

PhysicsMolecular dynamicsCondensed matter physicsHardware and ArchitectureLuttinger liquidQuantum dynamicsQuantum mechanicsPath integral molecular dynamicsGeneral Physics and AstronomySecond moment of areaAdiabatic processRandom walkQuantumComputer Physics Communications
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