Advanced capabilities for materials modelling with Quantum ESPRESSO by Giannozzi, P, Andreussi, O, Brumme, T, Bunau, O, Buongiorno Nardelli, M, Calandra, M, Car, R, Cavazzoni, C, Ceresoli, D, Cococcioni, M, Colonna, N, Carnimeo, I, Dal Corso, A, de Gironcoli, S, Delugas, P, DiStasio, R, Ferretti, A, Floris, A, Fratesi, G, Fugallo, G, Gebauer, R, Gerstmann, U, Giustino, F, Gorni, T, Jia, J, Kawamura, M, Ko, H, Kokalj, A, Küçükbenli, E, Lazzeri, M, Marsili, M, Marzari, N, Mauri, F, Nguyen, N, Nguyen, H, Otero-de-la-Roza, A, Paulatto, L, Poncé, S, Rocca, D, Sabatini, R, Santra, B, Schlipf, M, Seitsonen, A, Smogunov, A, Timrov, I, Thonhauser, T, Umari, P, Vast, N, Wu, X, Baroni, S

“…Quantum EXPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the-art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudopotential and projector-augmented-wave approaches. …”

Many-Electron QED with Redefined Vacuum Approach by Romain N. Soguel, Andrey V. Volotka, Dmitry A. Glazov, Stephan Fritzsche

“…The redefined vacuum approach, which is frequently employed in the many-body perturbation theory, proved to be a powerful tool for formula derivation. …”
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Engineering effective Hamiltonians by Holger Haas, Daniel Puzzuoli, Feihao Zhang, David G Cory

“…In the field of quantum control, effective Hamiltonian engineering is a powerful tool that utilizes perturbation theory to mitigate or enhance the effect that a variation in the Hamiltonian has on the evolution of the system. …”
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Causal shadow and non-local modular flow: from degeneracy to perturbative genesis by correlation by Liangyu Chen, Huajia Wang

“…In this paper, we study the perturbation theory of the causal shadows and their relation to the properties of the associated modular flows. …”
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Recent Advances in Microscopic Approaches to Nuclear Matter and Symmetry Energy by Francesca Sammarruca

“…We will present and discuss predictions based on chiral perturbation theory, where we employ consistent two- and three-body chiral interactions. …”
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Influence of Gain Saturation Effect on Transverse Mode Instability Considering Four-Wave Mixing by Haobo Li, Liangjin Huang, Hanshuo Wu, Zhiyong Pan, Pu Zhou

“…The gain saturation effect and fiber laser system parameters, such as seed power, pumping direction, and core numerical aperture, which have not been considered in the previous perturbation theory model, are also investigated. This work will enrich the perturbation theory model and extend its application scope in TMI mitigation strategies, providing guidance for understanding and suppressing TMI.…”
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Non-equilibrium quantum dynamics with collisional correlations by E Suraud, P-G Reinhard

“…This is done by first propagating two-body correlations in time-dependent perturbation theory for a certain time span, reducing the coherently correlated state into an incoherent sum of two-particle-two-hole states, and then sampling this state into an ensemble of mean-field states according to the jump probability obtained from perturbation theory. …”
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A comparative analysis of binding in ultralong-range Rydberg molecules by C Fey, M Kurz, P Schmelcher, S T Rittenhouse, H R Sadeghpour

“…A pseudopotential that yields exactly the results obtained with the quantum defect theory, i.e. beyond first order perturbation theory, is the regularized delta function potential. …”
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A spectral metric for collider geometry by Andrew J. Larkoski, Jesse Thaler

“…At lowest order in perturbation theory in electron-positron collisions, our metric is simply the summed squared invariant masses of the two event hemispheres. …”
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Nonlocal quantum effective actions in Weyl-Flat spacetimes by Teresa Bautista, André Benevides, Atish Dabholkar

“…Our action reduces to the nonlocal action obtained using the Barvinsky-Vilkovisky covariant perturbation theory in the regime R 2 ≪ ∇2 R for a typical curvature scale R, but has a greater range of validity effectively re-summing the covariant perturbation theory to all orders in curvatures. …”
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Thermal plasmon resonantly enhances electron scattering in Dirac/Weyl semimetals by Kozii, Vladyslav, Fu, Liang

“…We show that the perturbation theory diverges because of the long-range nature of the interaction, hence, thermally induced screening must be taken into account. …”
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Singularities of Scattering Matrices by Albert Schwarz

“…Our main result is the analysis of singularities of the integrands of integrals representing the matrix elements of the scattering matrix and the inclusive scattering matrix in perturbation theory. These results are proven for any quantum field theory in any dimension.…”
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Rare events are nonperturbative: Primordial black holes from heavy-tailed distributions by Sina Hooshangi, Mohammad Hossein Namjoo, Mahdiyar Noorbala

“…Moreover, it has been shown in some explicit single-field examples that the nonperturbative effects may lead to an exponential tail for the probability distribution function (PDF) of fluctuations responsible for PBH formation—in contrast to the PDF being Gaussian, as suggested by perturbation theory. In this paper, we advocate that the so-called δN formalism can be considered as a simple, yet effective, tool for the nonperturbative estimate of the tail of the PDF. …”
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Multiple couplings and renormalization scheme ambiguities by D.G.C. McKeon, Chenguang Zhao

“…We review how unlike models in which there is just one coupling constant there is no renormalization scheme in which the β-functions can be chosen to vanish beyond a certain order in perturbation theory, and also the β-functions always contain ambiguities beyond first order. …”
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A Farewell to Liouvillians by Oganesyan, V, Chalker, J, Sondhi, S

“…We next examine the relationship between Liouvillian perturbation theory and conventional calculations of disorder-averaged products of Green functions and show that each term in Liouvillian perturbation theory corresponds to a specific contribution to the two-particle Green function. …”

Introductory nanoscience / by 531914 Kuno, Masaru

Teoría de perturbaciones de Brillouin-Wigner: Oscilador armónico perturbado by D. Campos

“…The Brillouin-Wigner perturbation theory is applied to solve the eigenvalue equation of the perturbed Hamiltonian.…”
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Failure of the geometric approach prediction of excess work scaling for open and isolated quantum systems by Artur Soriani, Eduardo Miranda, Marcus V S Bonança

“…We approach this problem here in a rigorous and systematic fashion by means of the adiabatic perturbation theory of closed Hamiltonian quantum systems. …”
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A spectral metric for collider geometry by Larkoski, Andrew J., Thaler, Jesse

“…At lowest order in perturbation theory in electron-positron collisions, our metric is simply the summed squared invariant masses of the two event hemispheres. …”
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Deconstructing the Liouvillian approach to the quantum Hall plateau transition by Oganesyan, V, Chalker, J, Sondhi, S

“…We next examine the relationship between Liouvillian perturbation theory and conventional calculations of disorder-averaged products of Green functions and show that each term in Liouvillian perturbation theory corresponds to a specific contribution to the two-particle Green function. …”