Ground State of Liquid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

McMillan, W. L.

doi:10.1103/physrev.138.a442

Cited by 780 publications

(318 citation statements)

References 22 publications

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“…At a given Monte Carlo step, we uniformly sample M random positions, r ′ , within the simulation cell and, for each position and particle, compute in turn the above ratio [24]. The value of M depends on the size of the system and is determined to optimize the efficiency in sampling the momentum distribution.…”

Section: B Momentum Distribution and Compton Profilesmentioning

confidence: 99%

Quantum Monte Carlo calculation of Compton profiles of solid lithium

Filippi

Ceperley

1999

Phys. Rev. B

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Recent high resolution Compton scattering experiments in lithium have shown significant discrepancies with conventional band theoretical results. We present a pseudopotential quantum Monte Carlo study of electron-electron and electron-ion correlation effects on the momentum distribution of lithium. We compute the correlation correction to the valence Compton profiles obtained within Kohn-Sham density functional theory in the local density approximation and determine that electronic correlation does not account for the discrepancy with the experimental results. Our calculations lead do different conclusions than recent GW studies and indicate that other effects (thermal disorder, core-valence separation etc.) must be invoked to explain the discrepancy with experiments.

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Section: B Momentum Distribution and Compton Profilesmentioning

confidence: 99%

Quantum Monte Carlo calculation of Compton profiles of solid lithium

Filippi

Ceperley

1999

Phys. Rev. B

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“…Various theoretical and experimental works have been devoted in the past to study its ground state properties and in general the properties of the 4 He and other noble gas droplets. From the theoretical works we mention here those using Variational and Monte Carlo type methods [1][2][3][4][5], the Faddeev equations [6][7][8], and the hyperspherical approach [9][10][11]. From the experimental works we recall those of Refs.…”

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confidence: 99%

Ultralow energy scattering of a He atom off a He dimer

1997

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We present a new, mathematically rigorous, method suitable for bound state and scattering processes calculations for various three atomic or molecular systems where the underlying forces are of a hard-core nature. We employed this method to calculate the binding energies and the ultra-low energy scattering phase shifts below as well as above the break-up threshold for the three He-atom system. The method is proved to be highly successful and suitable for solving the three-body bound state and scattering problem in configuration space and thus it paves the way to study various three-atomic systems, and to calculate important quantities such as the cross-sections, recombination rates etc.LANL E-print physics/9802016. Published in Phys. Rev. A., 1997, v. 56, No. 3, pp. 1686 The 4 He trimer is of interest in various areas of Physical Chemistry and Molecular Physics, in particular such as the behavior of atomic clusters under collisions and BoseEinstein condensation. Various theoretical and experimental works have been devoted in the past to study its ground state properties and in general the properties of the 4 He and other noble gas droplets. From the theoretical works we mention here those using Variational and Monte Carlo type methods [1][2][3][4][5], the Faddeev equations [6][7][8], and the hyperspherical approach [9][10][11]. From the experimental works we recall those of Refs. [12][13][14][15] where molecular clusters consisting of a small number of noble gas atoms were investigated.Despite the efforts made to solve the He-trimer problem various questions such as the existence of Efimov states and the study of scattering processes at ultra-low energies still have not been satisfactorily addressed. In particular for scattering processes there are no works which we are aware of apart from a recent study concerning recombination rates [16]. There are various reasons for this the main one being the fact that the three-body calculations * On leave of absence from the

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“…Many-body simulation techniques such as the variational 1 and diffusion 2 quantum Monte Carlo ͑QMC͒ methods are capable of yielding highly accurate results for correlated systems. Large systems are normally modeled using a finite simulation cell subject to periodic boundary conditions.…”

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Elimination of Coulomb finite-size effects in quantum many-body simulations

et al. 1997

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A model interaction is introduced for quantum many-body simulations of Coulomb systems using periodic boundary conditions. The interaction gives much smaller finite size effects than the standard Ewald interaction and is also much faster to compute. Variational quantum Monte Carlo simulations of diamond-structure silicon with up to 1000 electrons demonstrate the effectiveness of our method. ͓S0163-1829͑97͒51408-1͔Many-body simulation techniques such as the variational 1 and diffusion 2 quantum Monte Carlo ͑QMC͒ methods are capable of yielding highly accurate results for correlated systems. Large systems are normally modeled using a finite simulation cell subject to periodic boundary conditions. This, however, introduces ''finite size effects'' which are often very important, particularly for systems with long ranged interactions such as the Coulomb interaction. In this paper we introduce a method for dealing with long ranged interactions in quantum many-body simulations which greatly reduces these finite size effects. This method is a generalization of one we developed earlier for homogeneous systems such as jellium. 3 We illustrate our method with variational QMC calculations on diamond-structure silicon. The ideas described in this paper are of wide generality and can be applied to other quantum many-body schemes, such as the HF and ''GW'' ͑Ref. 4͒ methods, and to long ranged interactions other than the Coulomb interaction.The finite size effects encountered in QMC calculations for electronic systems can be divided into two terms: ͑i͒ the independent particle finite size effect ͑IPFSE͒ and ͑ii͒ the Coulomb finite size effect ͑CFSE͒. 3,5 The IPFSE and CFSE are most easily defined with reference to results of local density approximation ͑LDA͒ calculations. The IPFSE is the difference between the LDA energies per atom in the finite and infinite systems and the CFSE is the remainder of the finite size error. Recently we presented a method 6 for reducing the IPFSE in insulating systems by using the ''special k-points'' method borrowed from band-structure theory. 7 This method reduces the IPFSE by an order of magnitude and leaves the CFSE as the dominant finite size effect. The CFSE, which is the subject of this work, arises from the long range of the Coulomb interaction and is therefore of wide significance in many-body simulations.We illustrate the CFSE by comparing the results of LDA and Hartree-Fock calculations. To define the LDA and HF energies for simulation cells with periodic boundary conditions we must specify the form of the model electronelectron interaction used. This interaction acts only between the charges within the simulation cell, but is intended to model the forces that would act in the center of an infinite array of identical copies of that cell. Unfortunately, sums of Coulomb 1/r potentials in extended systems are only conditionally convergent, and hence these forces are not uniquely defined until the boundary conditions at infinity have been specified. It is standard to calculate the potential...

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Ground State of LiquidHe4

Cited by 780 publications

References 22 publications

Quantum Monte Carlo calculation of Compton profiles of solid lithium

Quantum Monte Carlo calculation of Compton profiles of solid lithium

Ultralow energy scattering of a He atom off a He dimer

Elimination of Coulomb finite-size effects in quantum many-body simulations

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