Elastic constants of incommensurate solid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>4</mml:mn></mml:msup></mml:math>He from diffusion Monte Carlo simulations

Cazorla, Claudio; Lutsyshyn, Y.; Boronat, J.

doi:10.1103/physrevb.87.214522

Cited by 10 publications

(11 citation statements)

References 45 publications

(60 reference statements)

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“…For instance, the elastic properties of the incommensurate crystal in the limit of zero temperature have been analysed by Cazorla, Lutsyshyn, and Boronat (2013); it has been shown that when considering large vacancy concentrations (x v ∼ 1 %) the shear modulus of the solid undergoes a small reduction of just few percent with respect to the perfect crystal case.…”

Section: A Vacanciesmentioning

confidence: 99%

Simulation and understanding of atomic and molecular quantum crystals

2017

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Quantum crystals abound in the whole range of solid-state species. Below a certain threshold temperature the physical behavior of rare gases ( 4 He and Ne), molecular solids (H 2 and CH 4 ), and some ionic (LiH), covalent (graphite), and metallic (Li) crystals can be only explained in terms of quantum nuclear effects (QNE). A detailed comprehension of the nature of quantum solids is critical for achieving progress in a number of fundamental and applied scientific fields like, for instance, planetary sciences, hydrogen storage, nuclear energy, quantum computing, and nanoelectronics. This review describes the current physical understanding of quantum crystals formed by atoms and small molecules, as well as the wide palette of simulation techniques that are used to investigate them. Relevant aspects in these materials such as phase transformations, structural properties, elasticity, crystalline defects and the effects of reduced dimensionality, are discussed thoroughly. An introduction to quantum Monte Carlo techniques, which in the present context are the simulation methods of choice, and other quantum simulation approaches (e. g., path-integral molecular dynamics and quantum thermal baths) is provided. The overarching objective of this article is twofold. First, to clarify in which crystals and physical situations the disregard of QNE may incur in important bias and erroneous interpretations. And second, to promote the study and appreciation of QNE, a topic that traditionally has been treated in the context of condensed matter physics, within the broad and interdisciplinary areas of materials science.

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Section: A Vacanciesmentioning

confidence: 99%

Simulation and understanding of atomic and molecular quantum crystals

2017

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“…Specifically, the lattice vectors describing our simulation cell are a 1 = (L x , 0, 0), a 2 = (x 2 , L y , 0), and a 3 = (x 3 , y 3 , L z ), where x 3 represents the introduced tilt. The corresponding shear strain is η xz = x 3 /L z , and the resulting shear stress can be estimated as [35][36][37]:…”

Section: Methods B: Periodic Boundary Conditionsmentioning

confidence: 99%

Dislocation Structure and Mobility in Hcp Rare-Gas Solids: Quantum versus Classical

et al. 2018

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Abstract:We study the structural and mobility properties of edge dislocations in rare-gas crystals with the hexagonal close-packed (hcp) structure by using classical simulation techniques. Our results are discussed in the light of recent experimental and theoretical studies on hcp 4 He, an archetypal quantum crystal. According to our simulations classical hcp rare-gas crystals present a strong tendency towards dislocation dissociation into Shockley partials in the basal plane, similarly to what is observed in solid helium. This is due to the presence of a low-energy metastable stacking fault, of the order of 0.1 mJ/m 2 , that can get further reduced by quantum nuclear effects. We compute the minimum shear stress that induces glide of dislocations within the hcp basal plane at zero temperature, namely, the Peierls stress, and find a characteristic value of the order of 1 MPa. This threshold value is similar to the Peierls stress reported for metallic hcp solids (Zr and Cd) but orders of magnitude larger than the one estimated for solid helium. We find, however, that in contrast to classical hcp metals but in analogy to solid helium, glide of edge dislocations can be thermally activated at very low temperatures, T∼10 K, in the absence of any applied shear stress.

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“…2,34 The computational strategy that we followed to calculate the shear modulus C 44 was the same than in Refs. [35][36][37].…”

Section: B Diffusion Monte Carlomentioning

confidence: 99%

“…In order to quantify the importance of quantum nuclear effects on the calculation of the shear modulus, we carried out additional quantum DMC calculations (see Sec. II B and works [35][36][37] for details). To our surprise, we found that the quantum and classical shear modulii results are very similar.…”

Section: Elastic Propertiesmentioning

confidence: 99%

First-principles modeling of three-body interactions in highly compressed solid helium

Cazorla

Boronat

2015

Phys. Rev. B

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We present a set of three-body interaction models based on the Slater-Kirkwood (SK) potential that are suitable for the study of the energy, structural, and elastic properties of solid He4 at high pressure. Our effective three-body potentials are obtained from the fit to total energies and atomic forces computed with the van der Waals density functional theory method due to Grimme, and represent an improvement with respect to previously reported three-body interaction models. In particular, we show that some of the introduced SK three-body potentials reproduce closely the experimental equation of state and bulk modulus of solid helium up to a pressure of ~60 GPa, when used in combination with standard pairwise interaction models in diffusion Monte Carlo simulations. Importantly, we find that recent predictions reporting a surprisingly small variation of the kinetic energy and Lindeman ratio on quantum crystals under increasing pressure are likely to be artifacts deriving from the use of incomplete interaction models. Also, we show that the experimental variation of the shear modulus, C44, at pressures 0=P=25 GPa can be quantitatively described by our set of SK three-body potentials. At higher compression, however, the agreement between our C44 calculations and experiments deteriorates and thus we argue that higher order many-body terms in the expansion of the atomic interactions probably are necessary in order to better describe elasticity in very dense solid He4.Peer ReviewedPostprint (author's final draft

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Elastic constants of incommensurate solid4He from diffusion Monte Carlo simulations

Cited by 10 publications

References 45 publications

Simulation and understanding of atomic and molecular quantum crystals

Simulation and understanding of atomic and molecular quantum crystals

Dislocation Structure and Mobility in Hcp Rare-Gas Solids: Quantum versus Classical

First-principles modeling of three-body interactions in highly compressed solid helium

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