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We introduce a Gaussian approximation potential (GAP) for atomistic simulations of liquid and amorphous elemental carbon. Based on a machine-learning representation of the density-functional theory (DFT) potential-energy surface, such…

Materials Science · Physics 2017-03-08 Volker L. Deringer , Gábor Csányi

The superposition of atomic potentials (SAP) approach has recently been shown to be a simple and efficient way to initialize electronic structure calculations [S. Lehtola, J. Chem. Theory Comput. 15, 1593 (2019)]. Here, we study the…

Computational Physics · Physics 2020-04-13 Susi Lehtola , Lucas Visscher , Eberhard Engel

A recently developed finite element approach for fully numerical atomic structure calculations [S. Lehtola, Int. J. Quantum Chem. 119, e25945 (2019)] is extended to the description of atoms with spherically symmetric densities via…

Computational Physics · Physics 2020-01-30 Susi Lehtola

We combine classical heuristics with partial shadow tomography to enable efficient protocols for extracting information from correlated ab initio electronic systems encoded on quantum devices. By proposing the use of a correlation energy…

Quantum phase is not a direct observable and is usually determined by interferometric methods. We present a method to map complete electron wave functions, including internal quantum phase information, from measured single-state probability…

Mesoscale and Nanoscale Physics · Physics 2008-03-19 Christopher R. Moon , Laila S. Mattos , Brian K. Foster , Gabriel Zeltzer , Wonhee Ko , Hari C. Manoharan

In Kohn-Sham electronic structure computations, wave functions have singularities at nuclear positions. Because of these singularities, plane-wave expansions give a poor approximation of the eigenfunctions. In conjunction with the use of…

Numerical Analysis · Mathematics 2023-01-02 Xavier Blanc , Eric Cancès , Mi-Song Dupuy

The GRadient Ascent Pulse Engineering (GRAPE) method is widely used for optimization in quantum control. GRAPE is gradient search method based on exact expressions for gradient of the control objective. It has been applied to coherently…

Quantum Physics · Physics 2023-07-18 Vadim Petruhanov , Alexander Pechen

Accurate and efficient tools for calculating the ground state properties of interacting quantum systems are essential in the design of nanoelectronic devices. The exact diagonalization method fully accounts for the Coulomb interaction…

Mesoscale and Nanoscale Physics · Physics 2023-05-23 Calin-Andrei Pantis-Simut , Amanda Teodora Preda , Lucian Ion , Andrei Manolescu , George Alexandru Nemnes

We show that chemically-accurate potential energy surfaces (PESs) can be generated from quantum computers by measuring only the density along an adiabatic transition between different molecular geometries. In lieu of using phase estimation,…

Quantum Physics · Physics 2024-10-08 James Brown

Molecular ground-state simulation is one of the most promising fields for demonstrating practical quantum advantage on near-term quantum computers. However, the Variational Quantum Eigensolver (VQE), a leading algorithm for this task, still…

Quantum Physics · Physics 2025-07-08 Runhong He , Qiaozhen Chai , Xin Hong , Ji Guan , Guolong Cui , Shengbin Wang , Shenggang Ying

The potential energy surface (PES) is crucial for interpreting a variety of chemical reaction processes. However, predicting accurate PESs with high-level electronic structure methods is a challenging task due to the high computational…

Chemical Physics · Physics 2022-06-09 Yanxian Tao , Xiongzhi Zeng , Yi Fan , Jie Liu , Zhenyu Li , Jinlong Yang

We present a theory that efficiently describes the quantum dynamics of an electronic excitation that is coupled to a continuous, highly structured phonon environment. Based on a stochastic approach to non-Markovian open quantum systems, we…

Quantum Physics · Physics 2009-11-05 Jan Roden , Alexander Eisfeld , Wolfgang Wolff , Walter T. Strunz

Phase Resolved Optical Emission Spectroscopy (PROES) measurements combined with 1d3v Particle-in-Cell/Monte Carlo Collisions (PIC/MCC) simulations are used to study the electron power absorption and excitation/ionization dynamics in…

Plasma Physics · Physics 2022-09-28 A. Derzsi , P. Hartmann , M. Vass , B. Horváth , M. Gyulai , I. Korolov , J. Schulze , Z. Donkó

Quantum computers hold immense potential in the field of chemistry, ushering new frontiers to solve complex many body problems that are beyond the reach of classical computers. However, noise in the current quantum hardware limits their…

Quantum Physics · Physics 2024-03-20 Chayan Patra , Sonaldeep Halder , Rahul Maitra

Potential resonances are usually investigated either directly in the complex energy plane or indirectly in the complex angular momentum plane. Another formulation complementing these two is presented in this work. It is an indirect method…

Mathematical Physics · Physics 2009-11-10 A. D. Alhaidari

We introduce a novel class of coupled cluster (CC) methods that leverage the seniority concept to enhance efficiency and accuracy in electronic structure calculations. While existing approaches, such as the pair coupled cluster doubles…

We formulate a Hartree-Fock-LAPW method for electronic band structure calculations. The method is based on the Hartree-Fock-Roothaan approach for solids with extended electron states and closed core shells where the basis functions of…

Materials Science · Physics 2016-08-31 A. V. Nikolaev , P. N. Dyachkov

Sound analysis research has mainly been focused on speech and music processing. The deployed methodologies are not suitable for analysis of sounds with varying background noise, in many cases with very low signal-to-noise ratio (SNR). In…

Audio and Speech Processing · Electrical Eng. & Systems 2019-03-25 Nicola Strisciuglio , Mario Vento , Nicolai Petkov

We develop a general-purpose formulation, based on two-dimensional spectral integrals, for computing electromagnetic fields produced by arbitrarily-oriented dipoles in planar-stratified environments, where each layer may exhibit arbitrary…

Computational Physics · Physics 2014-11-27 K. Sainath , F. L. Teixeira , B. Donderici

A novel and highly efficient computational framework for reconstructing binary-type images suitable for models of various complexity seen in diverse biomedical applications is developed and validated. Efficiency in computational speed and…

Optimization and Control · Mathematics 2024-02-09 Paul R. Arbic , Vladislav Bukshtynov