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The free energies of vacancy pair formation and migration in MgO were computed via molecular dynamics using free-energy integrations and a non-empirical ionic model with no adjustable parameters. The intrinsic diffusion constant for MgO was…

Materials Science · Physics 2009-10-30 Joel Ita , Ronald E. Cohen

For free particles in a simple harmonic potential plus a weak anharmonicity, characterized by a set of anharmonic parameters, Newtonian mechanics asserts that there is a renormalization of the natural frequency of the periodic motion; and…

Statistical Mechanics · Physics 2023-07-04 Y. T. Liu , Y. H. Zhao , Y. Zhong , J. M. Shen , J. H. Zhang , Q. H. Liu

The PHASEGO package extracts the Helmholtz free energy from the phonon density of states obtained by the first-principles calculations. With the help of equation of states fitting, it reduces the Gibbs free energy as a function of…

Materials Science · Physics 2015-06-23 Zhong-Li Liu

We numerically investigate thermal transport at solid-solid interfaces with graded intermediate layers whose masses vary exponentially from one side to the other. Using Non-Equilibrium Green's Function and Non-Equilibrium Molecular Dynamics…

Accelerating the calculations of finite-temperature thermodynamic properties is a major challenge for rational materials design. Reliable methods can be quite expensive, limiting their effective applicability in autonomous high-throughput…

We introduce a non perturbative general approximation scheme (NGAS) that can handle interactions of any strength in quantum theory. This approach starts with an input Hamiltonian that can be solved exactly. The interaction effects are then…

Quantum Physics · Physics 2025-10-09 B. P. Mahapatra

We demonstrate the determination of anharmonic acoustic phonon properties via second-order Raman scattering exemplarily on copper iodide single crystals. The origin of multi-phonon features from the second-order Raman spectra was assigned…

We propose a new simple way to evaluate the effect of anharmonicity on a system's thermodynamic functions such as heat capacity. In this approach, the contribution of all potentially complicated anharmonic effects to constant-volume heat…

Statistical Mechanics · Physics 2015-06-15 E. I. Andritsos , E. Zarkadoula , A. E. Phillips , M. T. Dove , C. J. Walker , V. V. Brazhkin , K. Trachenko

The coherent states that describe the classical motion of a mechanical oscillator do not have well-defined energy, but are rather quantum superpositions of equally-spaced energy eigenstates. Revealing this quantized structure is only…

We investigate the dynamics of a macroscopic system which consists of an anharmonic subsystem embedded in an arbitrary harmonic lattice, including quenched disorder. Elimination of the harmonic degrees of freedom leads to a nonlinear…

Other Condensed Matter · Physics 2015-05-13 S. Aubry , R. Schilling

High-harmonic generation in solids has emerged as a powerful probe of ultrafast electron dynamics and lattice motion, and recent theoretical work has suggested that thermally driven lattice fluctuations can act as an effective source of…

Quantum entanglement and coherence often allow for protocols that outperform classical ones in estimating a system's parameter. When using infinite-dimensional probes (such as a bosonic mode), one could in principle obtain infinite…

The traditional atomistic Green's function (AGF) was formulated in the harmonic regime, preventing it from capturing the role of anharmonicity in interfacial thermal transport. Incorporating anharmonicity into AGF has long been desired but…

Mesoscale and Nanoscale Physics · Physics 2020-06-02 Jinghang Dai , Zhiting Tian

In many dynamical probes of a quantum system, quite often multiple eigenmodes are excited. Therefore, the experimental data can be quite messy due to the mixing of different modes, as well as the background noise, despite that each mode…

Quantum Physics · Physics 2019-04-11 Yadong Wu , Hui Zhai

The thermodynamics with medium effects expressed by the temperature- and density-dependent effective mass of quasiparticle is studied. Series difficulties and many wrangles in references due to the extraordinary parameter dependence are…

High Energy Physics - Theory · Physics 2007-09-04 Shaoyu Yin , Ru-Keng

Despite its simplicity, the single-trajectory thawed Gaussian approximation has proven useful for calculating vibrationally resolved electronic spectra of molecules with weakly anharmonic potential energy surfaces. Here, we show that the…

Chemical Physics · Physics 2024-09-26 Ēriks Klētnieks , Yannick Calvino Alonso , Jiří J. L. Vaníček

Quantum asymmetry is a physical resource which coincides with the amount of coherence between the eigenspaces of a generator responsible for phase encoding in interferometric experiments. We highlight an apparently counter-intuitive…

Motivated by the absence of experimental superconductivity in the metallic Pm-3n phase of AlH3 despite the predictions, we reanalyze its vibrational and superconducting properties at pressures above 99 GPa making use of first-principles…

Superconductivity · Physics 2021-05-05 Pugeng Hou , Francesco Belli , Raffaello Bianco , Ion Errea

Non-equilibrium path integral methods for computing quantum free energy differences are applied to a quantum particle trapped in a harmonic well of uniformly changing strength with the purpose of establishing the convergence properties of…

Statistical Mechanics · Physics 2009-11-13 Ramses van Zon , Lisandro Hernandez de la Pena , Gilles H. Peslherbe , Jeremy Schofield

Problems of heat transport are ubiquitous to various technologies such as power generation, cooling, electronics, and thermoelectrics. In this paper we advocate for the application of the quantum self-consistent reservoir method, which is…

Mesoscale and Nanoscale Physics · Physics 2019-01-30 Roya Moghaddasi Fereidani , Dvira Segal