Properties of Crystalline Argon and Neon in the Self-Consistent Phonon Approximation

Gillis, N. S.; Werthamer, N. R.; Kœhler, Thomas

doi:10.1103/physrev.165.951

Cited by 218 publications

(52 citation statements)

References 24 publications

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“…5,6 However, the QHA does not deal with phonon interaction effects, which can be treated by perturbation theory 7 when anharmonicity is not large, or by different self-consistent phonon theories for larger anharmonicities. 8,9,10,11 A different theoretical procedure is the Feynman path integral method, 12 which is well-suited to study thermodynamic properties of solids at temperatures lower than the Debye temperature Θ D , where the quantum nature of the atomic nuclei is relevant. The combination of path integrals with Monte Carlo (MC) sampling enables us to carry out quantitative and nonperturbative studies of anharmonic effects in solids.…”

Section: Introductionmentioning

confidence: 99%

Rare-gas solids under pressure: A path-integral Monte Carlo simulation

Herrero

Ramı́rez

2005

Phys. Rev. B

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Rare-gas solids (Ne, Ar, Kr, and Xe) under hydrostatic pressure up to 30 kbar have been studied by path-integral Monte Carlo simulations in the isothermal-isobaric ensemble. Results of these simulations have been compared with available experimental data and with those obtained from a quasiharmonic approximation (QHA). This comparison allows us to quantify the overall anharmonicity of the lattice vibrations and its influence on several structural and thermodynamic properties of rare-gas solids. The vibrational energy increases with pressure, but this increase is slower than that of the elastic energy, which dominates at high pressures. In the PIMC simulations, the vibrational kinetic energy is found to be larger than the corresponding potential energy, and the relative difference between both energies decreases as the applied pressure is raised. The accuracy of the QHA increases for rising pressure.

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Section: Introductionmentioning

confidence: 99%

Rare-gas solids under pressure: A path-integral Monte Carlo simulation

Herrero

Ramı́rez

2005

Phys. Rev. B

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“…We perform our ab initio investigation using a stochastic implementation of self-consistent phonon theory [24][25][26][27]. We show that the SnI 6 octahedra are stabilized against tilts and rotations by interacting with the renormalized vibrations of the Cs ions.…”

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confidence: 99%

Anharmonic stabilization and band gap renormalization in the perovskiteCsSnI3

2015

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Amongst the X(Sn,Pb)Y 3 perovskites currently under scrutiny for their photovoltaic applications, the cubic B-α phase of CsSnI 3 is arguably the best characterized experimentally. Yet, according to the standard harmonic theory of phonons, this deceptively simple phase should not exist at all due to rotational instabilities of the SnI 6 octahedra. Here, employing self-consistent phonon theory we show that these soft modes are stabilized at experimental conditions through anharmonic phonon-phonon interactions between the Cs ions and their iodine cages. We further calculate the renormalization of the electronic energies due to vibrations and find an unusual opening of the band gap, estimated as 0.24 and 0.11 eV at 500 and 300 K, which we attribute to the stretching of Sn-I bonds. Our work demonstrates the important role of temperature in accurately describing these materials.

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“…In principle, for example, an extension toward the self-consistent harmonic approximation is feasible. [24][25][26][27] We use the PHON and PHONOPY programs together with the Vienna Ab initio Simulation Package to calculate interatomic force constants to set up the dynamical matrix and then diagonalize it on a fine grid of the Brillouin zone to obtain the phonon frequencies and their corresponding densities of states. [28][29][30] The computational details are similar to those utilized in our previous study.…”

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confidence: 99%

Isotopic differentiation and sublattice melting in dense dynamic ice

2013

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The isotopes of hydrogen provide a unique exploratory laboratory for examining the role of zero point energy (ZPE) in determining the structural and dynamic features of the crystalline ices of water. There are two critical regions of high pressure: (i) near 1 TPa and (ii) near the predicted onset of metallization at around 5 TPa. At the lower pressure of the two, we see the expected small isotopic effects on phase transitions. Near metallization, however, the effects are much greater, leading to a situation where tritiated ice could skip almost entirely a phase available to the other isotopomers. For the higher pressure ices, we investigate in some detail the enthalpics of a dynamic proton sublattice, with the corresponding structures being quite ionic. The resistance toward diffusion of single protons in the ground state structures of high-pressure H 2 O is found to be large, in fact to the point that the ZPE reservoir cannot overcome these. However, the barriers toward a three-dimensional coherent or concerted motion of protons can be much lower, and the ensuing consequences are explored.

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Properties of Crystalline Argon and Neon in the Self-Consistent Phonon Approximation

Cited by 218 publications

References 24 publications

Rare-gas solids under pressure: A path-integral Monte Carlo simulation

Rare-gas solids under pressure: A path-integral Monte Carlo simulation

Anharmonic stabilization and band gap renormalization in the perovskiteCsSnI3

Isotopic differentiation and sublattice melting in dense dynamic ice

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