Search results for "Path integral Monte Carlo"

showing 4 items of 14 documents

Gibbs-ensemble path-integral Monte Carlo simulations of a mixed quantum-classical fluid

1995

We study a model fluid with classical translational degrees of freedom and internal quantum states in two spatial dimensions. The path-integral Monte Carlo and the Gibbs-ensemble Monte Carlo techniques are combined to investigate the liquid-gas coexistence region in this mixed quantum-classical system. A comparison with the phase diagram obtained in the canonical ensemble is also presented.

PhysicsHybrid Monte CarloQuantum Monte CarloMonte Carlo methodDynamic Monte Carlo methodMonte Carlo method in statistical physicsMonte Carlo integrationStatistical physicsPath integral Monte CarloMonte Carlo molecular modelingPhysical Review E
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A diffusion Monte Carlo study of small para-Hydrogen clusters

2007

Abstract An improved Monte Carlo diffusion model is used to calculate the ground state energies and chemical potentials of parahydrogen clusters of three to forty molecules, using two different p-H2-p-H2 interactions. The improvement is due to three-body correlations in the importance sampling, to the time step adjustment and to a better estimation of statistical errors. In contrast to path-integral Monte Carlo results, this method predicts no magic clusters other than that with thirteen molecules.

PhysicsPhysicsQC1-999FOS: Physical sciencesGeneral Physics and AstronomyFísica36.40.-cTime stepSpin isomers of hydrogenMolecular physicsmolecular clusterspara-hydrogen clusters67.40.db61.46.bcCluster (physics)Physics::Atomic and Molecular ClustersMoleculeDiffusion Monte CarloPhysics - Atomic and Molecular ClustersAtomic and Molecular Clusters (physics.atm-clus)Ground stateImportance samplingPath integral Monte Carlo
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Phase transitions and quantum effects in adsorbed monolayers

1996

Phase transitions in absorbed (two-dimensional) fluids and in absorbed layers of linear molecules are studied with a combination of path integral Monte Carlo (PIMC), Gibbs ensemble Monte Carlo (GEMC), and finite size scaling techniques. For a classical (nonadditive) hard-disk fluid the “critical” nonadditivities, where the entropy-driven phase separations set in, are presented. For a fluid with internal quantum states the gas-liquid coexistence region, tricritical, and triple points can be determined, and a comparison with density functional (DFT) results shows good agreement for the freezing densities. LinearN 2 molecules adsorbed on graphite (in the √3 × √3 structure) show a transition fr…

Quantum phase transitionCanonical ensemblePhase transitionMaterials sciencePhase (matter)Quantum mechanicsMonte Carlo methodPhysics::Chemical PhysicsQuantum Hall effectCondensed Matter PhysicsGround statePath integral Monte CarloInternational Journal of Thermophysics
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Phase diagram of a model adsorbate with internal quantum states

1992

Abstract An adsorbate in the strong binding and small corrugation limit is studied. The resulting two-dimensional fluid is treated in the adiabatic approximation: the translations of the heavy molecules are treated classically, whereas the molecular quantum degrees of freedom are modelled by interacting two state tunneling systems. The complete temperature/coverage phase diagram is obtained to a high degree of precision by a new combination of finite size scaling ideas with Path Integral Monte Carlo techniques. Even this simplified adsorbate model possesses a surprisingly complex phase diagram including first- and second-order transitions as well as tricritical and triple points. We identif…

Quantum phase transitionPhysicsCondensed matter physicsDegrees of freedom (physics and chemistry)Surfaces and InterfacesCondensed Matter PhysicsSurfaces Coatings and FilmsAdiabatic theoremQuantum statePhase (matter)Materials ChemistryPath integral Monte CarloQuantum tunnellingPhase diagramSurface Science
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