Wigner Gaussian dynamics: Simulating the anharmonic and quantum ionic motion

Siciliano, Antonio; Monacelli, Lorenzo; Caldarelli, Giovanni; Mauri, Francesco

doi:10.1103/physrevb.107.174307

Cited by 10 publications

(4 citation statements)

References 66 publications

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“…From here, we can go a step further and include some terms of the higher orders in the perturbation theory that stem from third and fourthorder anharmonic force constants (renormalized by anharmonicity as explained above), which are consistent with SSCHA [54][55][56][57] . The phonon Green's function (G μμ 0 ðq; ωÞ) in this case can be expressed as: G μμ 0 ðq; ΩÞ ¼ Ω 2 δ μμ 0 À D ð2Þ μμ 0 ðqÞ À Π μμ 0 ðq; ΩÞ h i À1 :…”

Section: Methodsmentioning

confidence: 94%

Large impact of phonon lineshapes on the superconductivity of solid hydrogen

Dangić,

Monacelli,

Bianco

et al. 2024

Commun Phys

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Phonon anharmonicity plays a crucial role in determining the stability and vibrational properties of high-pressure hydrides. Furthermore, strong anharmonicity can render phonon quasiparticle picture obsolete questioning standard approaches for modeling superconductivity in these material systems. In this work, we show the effects of non-Lorentzian phonon lineshapes on the superconductivity of high-pressure solid hydrogen. We calculate the superconducting critical temperature TC ab initio considering the full phonon spectral function and show that it overall enhances the TC estimate. The anharmonicity-induced phonon softening exhibited in spectral functions increases the estimate of the critical temperature, while the broadening of phonon lines due to phonon-phonon interaction decreases it. Our calculations also reveal that superconductivity emerges in hydrogen in the Cmca − 12 molecular phase VI at pressures between 450 and 500 GPa and explain the disagreement between the previous theoretical results and experiments.

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Section: Methodsmentioning

confidence: 94%

Large impact of phonon lineshapes on the superconductivity of solid hydrogen

Dangić,

Monacelli,

Bianco

et al. 2024

Commun Phys

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“…An ab initio estimation of the effective nonlinear coupling is needed to estimate the relative weights of the IKE and the EKE in a rigorous way. This would require a state-of-the-art extension of the available density functional theory (DFT) codes, which has been investigated only recently 60 and goes far beyond the scope of this work. For this reason, in the main text we decided to model the full Kerr response with only the electronic contribution by assuming that the ionic contribution has a similar spectral content, so as not to introduce any free adjustable parameter into our simulations.…”

Section: Methodsmentioning

confidence: 99%

Terahertz electric-field-driven dynamical multiferroicity in SrTiO3

Basini,

Pancaldi,

Wehinger

et al. 2024

Nature

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The emergence of collective order in matter is among the most fundamental and intriguing phenomena in physics. In recent years, the dynamical control and creation of novel ordered states of matter not accessible in thermodynamic equilibrium is receiving much attention1–6. The theoretical concept of dynamical multiferroicity has been introduced to describe the emergence of magnetization due to time-dependent electric polarization in non-ferromagnetic materials7,8. In simple terms, the coherent rotating motion of the ions in a crystal induces a magnetic moment along the axis of rotation. Here we provide experimental evidence of room-temperature magnetization in the archetypal paraelectric perovskite SrTiO3 due to this mechanism. We resonantly drive the infrared-active soft phonon mode with an intense circularly polarized terahertz electric field and detect the time-resolved magneto-optical Kerr effect. A simple model, which includes two coupled nonlinear oscillators whose forces and couplings are derived with ab initio calculations using self-consistent phonon theory at a finite temperature9, reproduces qualitatively our experimental observations. A quantitatively correct magnitude was obtained for the effect by also considering the phonon analogue of the reciprocal of the Einstein–de Haas effect, which is also called the Barnett effect, in which the total angular momentum from the phonon order is transferred to the electronic one. Our findings show a new path for the control of magnetism, for example, for ultrafast magnetic switches, by coherently controlling the lattice vibrations with light.

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“…Typically, variational approaches such as the selfconsistent harmonic approximation (SCHA) [168][169][170] are employed in non-perturbative settings. In the last couple of years, the method has also been generalized to include time dependent effects to simulate nuclear dynamics [171,172]. However, this approach is computationally intensive and a stochastic version of the SCHA (called the SSCHA) has been explored [167,[173][174][175][176] to determine anharmonic free energy, thermal transport and superconducting properties.…”

Section: Phonon Damping From First Principlesmentioning

confidence: 99%

Anharmonic theory of superconductivity and its applications to emerging quantum materials

Setty,

Baggioli,

Zaccone

2024

J. Phys.: Condens. Matter

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The role of anharmonicity on superconductivity has often been disregarded in the past. Recently, it has been recognized that anharmonic decoherence could play a fundamental role in determining the superconducting properties (electron-phonon coupling, critical temperature, etc) of a large class of materials, including systems close to structural soft-mode instabilities, amorphous solids and metals under extreme high-pressure conditions.Here, we review recent theoretical progress on the role of anharmonic effects, and in particular certain universal properties of anharmonic damping, on superconductivity. Our focus regards the combination of microscopic-agnostic effective theories for bosonic mediators with the well-established BCS theory and Migdal-Eliashberg theory for superconductivity. We discuss in detail the theoretical frameworks, their possible implementation within first-principles methods, and the experimental probes for anharmonic decoherence. Finally, we present several concrete applications to emerging quantum materials, including hydrides, ferroelectrics and systems with charge density wave instabilities.

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Wigner Gaussian dynamics: Simulating the anharmonic and quantum ionic motion

Cited by 10 publications

References 66 publications

Large impact of phonon lineshapes on the superconductivity of solid hydrogen

Large impact of phonon lineshapes on the superconductivity of solid hydrogen

Terahertz electric-field-driven dynamical multiferroicity in SrTiO3

Anharmonic theory of superconductivity and its applications to emerging quantum materials

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