Quantum Monte Carlo Simulation of Overpressurized Liquid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts /><mml:none /><mml:mn>4</mml:mn></mml:mmultiscripts></mml:math>

Vranješ, Leandra; Boronat, J.; Casulleras, J.; Cazorla, Claudio

doi:10.1103/physrevlett.95.145302

Cited by 38 publications

(51 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance, at density ρ = 0.02940Å −3 we get in our simulation 4 He given in Ref. 12 E/N = (−5.48 ± 0.03) K. If we perform a PIGS simulation at the same density and with the same choice for the initial trial wave function (in both cases, we choose in Eq. 1 Ψ T = 1) but starting the computation from a hcp crystalline configuration, we get E/N = (−5.95 ± 0.02) K. The disagreement of the two results for E/N indicates that, in PIGS simulations, initial conditions for the atomic configuration influence the evolution of the system: in particular, a sensible choice of the initial conditions speed up the convergence of the system to the real equilibrium state.…”

Section: Resultsmentioning

confidence: 99%

“…Diffusion Monte Carlo technique, for instance, has provided estimations of n 0 in liquid 4 He on a wide range of pressures. [10][11][12] This method, however, suffers from the choice of a variational ansatz necessary for the importance sampling whose influence on ρ 1 (r) cannot be completely removed. Reptation Quantum Monte Carlo (RQMC) has also been used for this purpose, 13 but the calculated value of n 0 at SVP lies somewhat below the recent PIMC value 9 at T = 1 K noted above.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Condensate Fraction in Liquid 4He at Zero Temperature

Rota

Boronat

2011

J Low Temp Phys

Self Cite

View full text Add to dashboard Cite

We present results of the one-body density matrix ρ 1 (r) and the condensate fraction n 0 of liquid 4 He calculated at zero temperature by means of the Path Integral Ground State Monte Carlo method. This technique allows to generate a highly accurate approximation for the ground state wave function Ψ 0 in a totally model-independent way, that depends only on the Hamiltonian of the system and on the symmetry properties of Ψ 0 . With this unbiased estimation of ρ 1 (r), we obtain precise results for the condensate fraction n 0 and the kinetic energy K of the system. The dependence of n 0 with the pressure shows an excellent agreement of our results with recent experimental measurements. Above the melting pressure, overpressurized liquid 4 He shows a small condensate fraction that has dropped to 0.8% at the highest pressure of p = 87 bar.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Condensate Fraction in Liquid 4He at Zero Temperature

Rota

Boronat

2011

J Low Temp Phys

Self Cite

View full text Add to dashboard Cite

show abstract

“…[35]. The solid line represents the fit to DMC calculations [29] with the HFD-B(HE) potential [36]. The curve accurately represents the results from the spinodal density (0.264 σ -3 ) right up to the highest density of 0.650 σ -3 (σ=2.556 Å).…”

Section: Nuclear Matter Propertiesmentioning

confidence: 99%

“…Unlike nuclear matter, a hypothetical system, liquid 4 He is a real self bound saturating system. Exact GFMC and DMC calculations with accurate quantum mechanical Hamiltonian give results indistinguishable from experiment [28,29]. With the same Hamiltonian liquid 4 He droplets, in various respects analogous to atomic nuclei, have been studied with the exact GFMC/DMC methods for 3≤N≤112 where N is the number of 4 He atoms [30,31].…”

Section: Nuclear Matter Propertiesmentioning

confidence: 99%

Nuclear matter properties, phenomenological theory of clustering at the nuclear surface, and symmetry energy

et al. 2011

View full text Add to dashboard Cite

We present a phenomenological theory of nuclei that incorporates clustering at the nuclear surface in a general form. The theory explains the recently extracted large symmetry energy by Natowitz et al. at low densities of nuclear matter and is fully consistent with the static properties of nuclei. In phenomenological way clusters of all sizes, shapes along with medium modifications are included. Symmetric nuclear matter properties are discussed in detail. Arguments are given that lead to an equation of state of nuclear matter consistent with clustering in the low density region. We also discuss properties of asymmetric nuclear matter. Because of clustering, an interesting interpretation of the equation of state of asymmetric nuclear matter emerges. As a framework, an extended version of Thomas Fermi theory is adopted for nuclei which also contain phenomenological pairing and Wigner contributions. This theory connects the nuclear matter equation of state, which incorporate clustering at low densities, with clustering in nuclei at the nuclear surface. Calculations are performed for various equation of state of nuclear matter. We consider measured binding energies of 2149 nuclei for N, Z ≥ 8. The importance of quartic term in symmetry energy is demonstrated at and below the saturation density of nuclear matter. It is shown that it is largely related to the use of, ab initio, realistic equation of state of neutron matter, particularly the contribution arising from the three neutron interaction and somewhat to clustering.Reasons for these are discussed. Because of clustering the neutron skin thickness in nuclei is found to reduce significantly. Theory predicts new situations and regimes to be explored both theoretically and experimentally. *

show abstract

“…At zero temperature, the phases of 4 He can be studied in an essentially exact form with a family of projector methods, including Green's-function Monte Carlo [17,18], diffusion Monte Carlo [19], and path-integral ground-state Monte Carlo [20]. These methods properly describe the phase transition in helium, and can provide insight on the nature of its ground state [21,22].…”

mentioning

confidence: 99%

Quantum phase transition with a simple variational ansatz

et al. 2014

Self Cite

View full text Add to dashboard Cite

We study the zero-temperature quantum phase transition between liquid and hcp solid 4 He. We use the variational method with a simple yet exchange-symmetric and fully explicit wave function. It is found that the optimized wave function undergoes spontaneous symmetry breaking and describes the quantum solidification of helium at 22 atm. The explicit form of the wave function allows us to consider various contributions to the phase transition. We find that the employed wave function is an excellent candidate for describing both a first-order quantum phase transition and the ground state of a Bose solid. Properties of solid 4 He have regained attention due to a host of unexpected physics discovered in the past decade [1][2][3][4][5][6][7][8]. Most of the new features occur close to absolute zero and are believed to be primarily driven by quantum effects. Consequently, the solidification of 4 He came under renewed scrutiny. The role of quantum statistics in the transition location has been recently revisited in Ref. [9]. At small but nonzero temperatures, indistinguishability of particles destabilizes the quantum solid. Distinguishable particles, on the other hand, would solidify even at low pressures, with the phase diagram reminiscent of the Pomeranchuk effect [10,11]. The feature was dubbed in [9] as thermocrystallization. A similar effect was seen numerically for the Wigner-crystallization of a two-dimensional Coulomb system [12]. The solidification of 4 He at zero temperature was revisited in Ref. [13] with the density functional theory (DFT). Results were improved compared with previous DFT studies.In this paper, we show that the quantum solidification of 4 He can be considered variationally, with a single explicit wave-function which selects the phase through optimization of the thermodynamic potential. Quite surprisingly, we find that the phase transition is predicted properly, given the relative simplicity of the wave function. While the variational treatment is used for quantum phase transitions at the mean-field level [14], it is relatively uncommon that a (discontinuous) transition can be described with a microscopic wave function. The finding is also interesting in light of growing interest to the first-order quantum phase transitions [15,16].At zero temperature, the phases of 4 He can be studied in an essentially exact form with a family of projector methods, including Green's-function Monte Carlo [17,18] [23,24], and describe the transition [25][26][27] and coexistence [28] between the two phases. The SWFs can be seen as representing a single step of a projection calculation [23]. The projection is carried out by performing the numerical integration of the shadow degrees of freedom. In this sense, the SWF is not fully explicit, as one cannot write down the result of such an integration. We consider SWF calculations as a class of their own, in between the exact projection methods and the simple and fully explicit wave function used here.Highly effective wave functions have been developed over the years...

show abstract

Quantum Monte Carlo Simulation of Overpressurized LiquidHe4

Cited by 38 publications

References 23 publications

Condensate Fraction in Liquid 4He at Zero Temperature

Condensate Fraction in Liquid 4He at Zero Temperature

Nuclear matter properties, phenomenological theory of clustering at the nuclear surface, and symmetry energy

Quantum phase transition with a simple variational ansatz

Contact Info

Product

Resources

About