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Please use this identifier to cite or link to this item: http://doi.org/10.25358/openscience-2459
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dc.contributor.authorKrajewski, Florian
dc.date.accessioned2002-12-31T23:00:00Z
dc.date.available2003-01-01T00:00:00Z
dc.date.issued2003
dc.identifier.urihttps://openscience.ub.uni-mainz.de/handle/20.500.12030/2461-
dc.description.abstractA path integral simulation algorithm which includes a higher-order Trotter approximation (HOA)is analyzed and compared to an approach which includes the correct quantum mechanical pair interaction (effective Propagator (EPr)). It is found that the HOA algorithmconverges to the quantum limit with increasing Trotter number P as P^{-4}, while the EPr algorithm converges as P^{-2}.The convergence rate of the HOA algorithm is analyzed for various physical systemssuch as a harmonic chain,a particle in a double-well potential, gaseous argon, gaseous helium and crystalline argon. A new expression for the estimator for the pair correlation function in the HOA algorithm is derived. A new path integral algorithm, the hybrid algorithm, is developed.It combines an exact treatment of the quadratic part of the Hamiltonian and thehigher-order Trotter expansion techniques.For the discrete quantum sine-Gordon chain (DQSGC), it is shown that this algorithm works more efficiently than all other improved path integral algorithms discussed in this work. The new simulation techniques developed in this work allow the analysis of theDQSGC and disordered model systems in the highly quantum mechanical regime using path integral molecular dynamics (PIMD)and adiabatic centroid path integral molecular dynamics (ACPIMD).The ground state phonon dispersion relation is calculated for the DQSGC by the ACPIMD method.It is found that the excitation gap at zero wave vector is reduced by quantum fluctuations. Two different phases exist: One phase with a finite excitation gap at zero wave vector, and a gapless phase where the excitation gap vanishes.The reaction of the DQSGC to an external driving force is analyzed at T=0.In the gapless phase the system creeps if a small force is applied, and in the phase with a gap the system is pinned. At a critical force, the systems undergo a depinning transition in both phases and flow is induced. The analysis of the DQSGC is extended to models with disordered substrate potentials. Three different cases are analyzed: Disordered substrate potentials with roughness exponent H=0, H=1/2,and a model with disordered bond length. For all models, the ground state phonon dispersion relation is calculated.en_GB
dc.language.isoeng
dc.rightsInCopyrightde_DE
dc.rights.urihttps://rightsstatements.org/vocab/InC/1.0/
dc.subject.ddc530 Physikde_DE
dc.subject.ddc530 Physicsen_GB
dc.titleNew path integral simulation algorithms and their application to creep in the quantum sine-Gordon chainen_GB
dc.typeDissertationde_DE
dc.identifier.urnurn:nbn:de:hebis:77-4711
dc.identifier.doihttp://doi.org/10.25358/openscience-2459-
jgu.type.dinitypedoctoralThesis
jgu.type.versionOriginal worken_GB
jgu.type.resourceText
jgu.organisation.departmentFB 08 Physik, Mathematik u. Informatik-
jgu.organisation.year2003
jgu.organisation.number7940-
jgu.organisation.nameJohannes Gutenberg-Universität Mainz-
jgu.rights.accessrightsopenAccess-
jgu.organisation.placeMainz-
jgu.subject.ddccode530
opus.date.accessioned2002-12-31T23:00:00Z
opus.date.modified2002-12-31T23:00:00Z
opus.date.available2003-01-01T00:00:00
opus.organisation.stringFB 08: Physik, Mathematik und Informatik: FB 08: Physik, Mathematik und Informatikde_DE
opus.identifier.opusid471
opus.institute.number0800
opus.metadataonlyfalse
opus.type.contenttypeDissertationde_DE
opus.type.contenttypeDissertationen_GB
jgu.organisation.rorhttps://ror.org/023b0x485
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