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The quasi-harmonic approximation (QHA) is a powerful method that uses the volume dependence of non-interacting phonons to compute the free energy of materials at high pressures (P) and temperatures (T). However, anharmonicity, electronic…

计算物理 · 物理学 2023-08-09 Hongjin Wang , Jingyi Zhuang , Zhen Zhang , Qi Zhang , Renata M. Wentzcovitch

The Bethe-Salpeter formalism represents the most accurate method available nowadays for computing neutral excitation energies and optical spectra of crystalline systems from first principles. Bethe-Salpeter calculations yield very good…

材料科学 · 物理学 2016-05-04 Yannick Gillet , Matteo Giantomassi , Xavier Gonze

Gaussian wavepackets are a popular tool for semiclassical analyses of classically chaotic systems. We demonstrate that they are extremely powerful in the semiquantal analysis of such systems, too, where their dynamics can be recast in an…

chao-dyn · 物理学 2009-10-22 Arjendu K. Pattanayak , William C. Schieve

We present a scheme to controllably improve the accuracy of tight-binding Hamiltonian matrices derived by projecting the solutions of plane-wave ab initio calculations on atomic orbital basis sets. By systematically increasing the…

Approximate methods to estimate solutions to the radiative transfer equation are essential for the understanding of atmospheres of exoplanets and brown dwarfs. The simplest and most popular choice is the "two-stream method" which is often…

地球与行星天体物理 · 物理学 2023-04-12 Caoimhe M. Rooney , Natasha E. Batalha , Mark S. Marley

A mixed semiclassical initial value representation expression for spectroscopic calculations is derived. The formulation takes advantage of the time-averaging filtering and the hierarchical properties of different trajectory based…

量子物理 · 物理学 2016-05-27 Max Buchholz , Frank Grossmann , Michele Ceotto

We present a self-consistent approach for computing the correlated quasiparticle spectrum of charged excitations in iterative $\mathcal{O}[N^5]$ computational time. This is based on the auxiliary second-order Green's function approach [O.…

化学物理 · 物理学 2020-10-05 Oliver J. Backhouse , George H. Booth

Based on realistic simulations, we propose an hybrid method to reconstruct the lensing potential power spectrum, directly on PLANCK-like CMB frequency maps. It implies using a large galactic mask and dealing with a strong inhomogeneous…

宇宙学与河外天体物理 · 物理学 2015-03-20 S. Plaszczynski , A. Lavabre , L. Perotto , J. -L. Starck

Single-Hessian Gaussian wavepacket dynamics (GWD) significantly reduces the computational burden of Heller's local harmonic GWD, while maintaining comparable accuracy in approximating vibronic spectra. Here, we provide a new, symplectic…

化学物理 · 物理学 2026-05-11 Davide Barbiero , Jiří J. L. Vaníček

The free energy and other thermodynamic properties of hexagonal-close-packed iron are calculated by direct {\em ab initio} methods over a wide range of pressures and temperatures relevant to the Earth's core. The {\em ab initio}…

凝聚态物理 · 物理学 2007-05-23 D. Alfe` , G. D. Price , M. J. Gillan

The transmission of acoustic phonons is an important element in the design and performance of nano-mechanical devices operating in the mesoscopic limit. Analytic expressions for the power transmission coefficient, T, exist only in the…

应用物理 · 物理学 2019-03-27 John Bartlett , Karwan Rostem , Edward Wollack

We developed a general framework for hybrid quantum-classical computing of molecular and periodic embedding approaches based on an orbital space separation of the fragment and environment degrees of freedom. We demonstrate its potential by…

The generalized pseudospectral method is employed for the accurate calculation of eigenvalues, densities and expectation values for the spiked harmonic oscillators. This allows \emph{nonuniform} and \emph{optimal} spatial discretization of…

量子物理 · 物理学 2015-06-16 Amlan K. Roy

The twisted Gaussian Schell Model describes a family of partially coherent beams that present several interesting characteristics, and as such have attracted attention in classical and quantum optics. Recent techniques have been…

A method is presented for tracing the locus of a specific peak in the frequency response under variation of a parameter. It is applicable to periodic, steady-state vibrations of harmonically forced nonlinear mechanical systems. It operates…

计算工程、金融与科学 · 计算机科学 2021-01-01 Alwin Förster , Malte Krack

We propose a hybrid Finite Volume (FV) - Spectral Element Method (SEM) for modelling aeroacoustic phenomena based on the Lighthill's acoustic analogy. First the fluid solution is computed employing a FV method. Then, the sound source term…

While pseudospectral (PS) methods can feature very high accuracy, they tend to be severely limited in terms of geometric flexibility. Application of global radial basis functions overcomes this, however at the expense of problematic…

数值分析 · 数学 2017-05-09 Pankaj K Mishra , Sankar K Nath , Gregor Kosec , Mrinal K Sen

While the coherent control of two level quantum systems ---qubits--- is now standard, their continuum electronic equivalents ---flying qubits--- are much less developed. A first step in this direction has been achieved in DC interferometry…

介观与纳米尺度物理 · 物理学 2018-11-21 Benoit Rossignol , Thomas Kloss , Pacome Armagnat , Xavier Waintal

We present a general framework for the efficient simulation of realistic fermionic systems with modern machine learning inspired representations of quantum many-body states, towards a universal tool for ab initio electronic structure. These…

强关联电子 · 物理学 2023-05-16 Yannic Rath , George H. Booth