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High-order harmonic generation (HHG) results from strong-field laser matter interaction and it is one of the main processes that are used to extract electron structural and dynamical information about the atomic or molecular targets with…

The development of a novel exact two-component (X2C) scheme with the inclusion of the picture-change correction for the fluctuation potential, the X2Ccorr scheme, is reported, hereby establishing a hierarchy of X2C schemes with systematic…

Chemical Physics · Physics 2026-03-02 Xubo Wang , Sen Wang , Yixuan Wu , Lan Cheng

By using stochastic ensembles of walkers in physical and in one-body Hilbert spaces the recently proposed time-dependent quantum Monte Carlo (TDQMC) method offers the unique capability to calculate one-body density matrices at fully…

Quantum Physics · Physics 2025-02-07 Ivan P. Christov

We derive and implement analytic nuclear gradients and derivative couplings for a constrained Complete Active Space Self-Consistent Field with a small active space designed to model electron or hole transfer. Using a Lagrangian formalism,…

Computational Physics · Physics 2025-09-01 Tian Qiu , Joseph E. Subotnik

We apply the theory of high-order harmonic generation by low-frequency laser fields in the strong field approximation to the study of the spatial and temporal coherence properties of the harmonics. We discuss the role of dynamically induced…

Quantum Physics · Physics 2007-05-23 Pascal Salières , Anne L'Huillier , Philippe Antoine , Maciej Lewenstein

A multiscale model based on the coupling of the multiconfigurational self-consistent field (MCSCF) method and the classical atomistic polarizable Fluctuating Charges (FQ) force field is presented. The resulting MCSCF/FQ approach is…

In this report, a novel methodology based on the static coherent states approach is introduced with the capability of calculating various strong-field laser-induced nonlinearities in full dimensional single-electron molecular systems; an…

Quantum Physics · Physics 2019-10-10 Mohammadreza Eidi , Mohsen Vafaee , Hamed Koochaki Kelardeh , Alexandra Landsman

We develop and exactly solve a model for electrons driven by pulsed or continuous ac fields. The theory includes both the photoexcitation process as well as the subsequent acceleration of the electrons. In the case of an ac response, we…

Strongly Correlated Electrons · Physics 2015-01-12 W. S. Shen , T. P. Devereaux , J. K. Freericks

Time-dependent quantum chemical methods coupled to Gaussian basis sets are gaining popularity in modeling the electron dynamics of atoms and molecules interacting with intense laser fields. Two approaches most widely used for this purpose,…

Chemical Physics · Physics 2023-01-18 Aleksander P. Woźniak , Maciej Lewenstein , Robert Moszyński

High-harmonic generation in solids allows probing and controlling electron dynamics in crystals on few femtosecond timescales, paving the way to lightwave electronics. In the spatial domain, recent advances in the real-space interpretation…

A particle method for reproducing the phase space of collisionless stellar systems is described. The key idea originates in Liouville's theorem which states that the distribution function (DF) at time t can be derived from tracing necessary…

Astrophysics · Physics 2009-10-30 Shunsuke Hozumi

Time-domain analysis of harmonic fields with sub-cycle resolution is now experimentally viable due to the emergence of sensitive, on-chip techniques for petahertz-scale optical-field sampling. We demonstrate how such a time-domain,…

The present work introduces a robust way to generate attosecond pulses with tunable ellipticity via high-order harmonic generation by co-rotating $\omega - 2\omega$ bicircular laser fields. The total electric field of the laser fields…

Optics · Physics 2023-05-02 Rambabu Rajpoot , Amol R. Holkundkar , Navdeep Rana , Gopal Dixit

In this work we describe the Correlative Method of Unsymmetrized Self-Consistent Field (CUSF). This method is based on a set of nonlinear integrodifferential equations for the one-particle configurational distribution functions and for the…

Statistical Mechanics · Physics 2019-06-14 Clóves Gonçalves Rodrigues , André Luiz Cardoso da Silva

An interesting property of high harmonic generation in solids is its laser polarization dependent nature which in turn provides information about the crystal and band structure of the generation medium. Here we report on the linear…

Aiming at the investigation of above-threshold ionization in super-strong laser fields with highly charged ions, we develop a Coulomb-corrected strong field approximation (SFA). The influence of the Coulomb potential of the atomic core on…

Atomic Physics · Physics 2015-05-19 Michael Klaiber , Enderalp Yakaboylu , Karen Z. Hatsagortsyan

The atomistic resolution recently achieved by ultrafast spectroscopies demands corresponding theoretical advances. Real-time time-dependent density-functional theory (RT-TDDFT) with Ehrenfest dynamics offers an optimal trade-off between…

Materials Science · Physics 2022-10-19 Jannis Krumland , Matheus Jacobs , Caterina Cocchi

Modeling chemical reactions with quantum chemical methods is challenging when the electronic structure varies significantly throughout the reaction, as well as when electronic excited states are involved. Multireference methods such as…

Based upon our previous works (Eur.Phys.J.D 6, 319(1999); Chin.Phys.Lett. 18, 236(2001)), we develop a classical approach to calculate the high-order harmonic generation of the laser driven atoms and molecules. The Coulomb singularities in…

Atomic Physics · Physics 2007-05-23 Chaohong Lee , Yiwu Duan , Wing-Ki Liu , Jian-Min Yuan , Lei Shi , Xiwen Zhu , Kelin Gao

In this study, we investigate second- and third-harmonic generation processes in Au nanorod systems using the real-time time-dependent density functional tight binding method. Our study focuses on the computation of nonlinear signals based…

Optics · Physics 2024-09-18 Sajal Kumar Giri , George C. Schatz