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The Bethe-Salpeter Equation (BSE) can be applied to compute from first-principles optical spectra that include the effects of screened electron-hole interactions. As input, BSE calculations require single-particle states, quasiparticle…

Materials Science · Physics 2020-01-01 Joshua Elliott , Nicola Colonna , Margherita Marsili , Nicola Marzari , Paolo Umari

We develop a method to estimate the power spectrum of a stochastic process on the sphere from data of limited geographical coverage. Our approach can be interpreted either as estimating the global power spectrum of a stationary process when…

Instrumentation and Methods for Astrophysics · Physics 2013-06-17 Mark A. Wieczorek , Frederik J. Simons

We propose a method for calculating exciton spectra and wavefunctions for model lattice Hamiltonians, based on real-space electron-hole propagators. We verify that our results agree with those of the continuum approximation in the limit of…

Strongly Correlated Electrons · Physics 2026-03-19 Man-Yat Chu , Mona Berciu

Linear and non-linear spectroscopies are powerful tools used to investigate the energetics and dynamics of electronic excited states of both molecules and crystals. While highly accurate \emph{ab initio} calculations of molecular spectra…

Materials Science · Physics 2019-09-26 Alan M. Lewis , Timothy C. Berkelbach

We present a method to construct an efficient approximation to the bare exchange and screened direct interaction kernels of the Bethe-Salpeter Hamiltonian for periodic solid state systems via the interpolative separable density fitting…

Computational Physics · Physics 2020-06-24 F. Henneke , L. Lin , C. Vorwerk , C. Draxl , R. Klein , C. Yang

An ab initio Hartree-Fock approach aimed at directly obtaining the localized orthogonal orbitals (Wannier functions) of a crystalline insulator is described in detail. The method is used to perform all-electron calculations on the ground…

Condensed Matter · Physics 2009-10-30 Alok Shukla , Michael Dolg , Peter Fulde , Hermann Stoll

Theoretical and numerical calculations of the optical absorption spectra of excitons interacting with longitudinal-optical phonons in quasi-2D polar semiconductors are presented. In II-VI semiconductor quantum wells, exciton binding energy…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 F. J. Rodriguez

We present a new code to evaluate thermoelectric and electronic transport properties of extended systems with a maximally-localized Wannier function basis set. The semiclassical Boltzmann transport equations for the homogeneous infinite…

Materials Science · Physics 2013-11-22 Giovanni Pizzi , Dmitri Volja , Boris Kozinsky , Marco Fornari , Nicola Marzari

Wannier functions have become a powerful tool in the electronic structure calculations of extended systems. The generalized Pipek-Mezey Wannier functions exhibit appealing characteristics (e.g., reaching an optimal localization and the…

Materials Science · Physics 2022-04-04 Guorong Weng , Mariya Romanova , Arsineh Apelian , Hanbin Song , Vojtěch Vlček

A major obstacle for computing optical spectra of solids is the lack of reliable approximations for capturing excitonic effects within time-dependent density-functional theory. We show that the trustful prediction of strongly bound…

We present an alternative formalism for calculating the maximally localized Wannier functions in crystalline solids, obtaining an expression which is extremely simple and general. In particular, our scheme is exactly invariant under…

Materials Science · Physics 2011-03-03 Massimiliano Stengel , Nicola A. Spaldin

A recently proposed approach for performing electronic-structure calculations on crystalline insulators in terms of localized orthogonal orbitals is applied to the oxides of lithium and sodium, Li2O and Na2O. Cohesive energies, lattice…

Condensed Matter · Physics 2009-10-31 Alok Shukla , Michael Dolg , Peter Fulde , Hermann Stoll

We perform a theoretical study of the nonlinear optical response of an ultrathin film consisting of oriented linear aggregates. A single aggregate is described by a Frenkel exciton Hamiltonian with uncorrelated on-site disorder. The exciton…

Disordered Systems and Neural Networks · Physics 2007-10-25 J. A. Klugkist , V. A. Malyshev , J. Knoester

We present a method to compute optical spectra and exciton binding energies of molecules and solids based on the solution of the Bethe-Salpeter equation (BSE) and the calculation of the screened Coulomb interaction in finite field. The…

Materials Science · Physics 2019-06-19 Ngoc Linh Nguyen , He Ma , Marco Govoni , Francois Gygi , Giulia Galli

We describe a real-space approach to the calculation of the properties of an insulating crystal in an applied electric field, based on the iterative determination of the Wannier functions (WF's) of the occupied bands. It has been recently…

Condensed Matter · Physics 2009-10-22 R. W. Nunes , David Vanderbilt

Solving the Bethe-Salpeter equation (BSE) for the optical polarization functions is a first principles means to model optical properties of materials including excitonic effects. One almost ubiquitously used approximation neglects the…

Materials Science · Physics 2023-07-11 Xiao Zhang , Joshua A. Leveillee , André Schleife

An optical absorption spectrum constitutes one of the most fundamental material characteristics, with relevant applications ranging from material identification to energy harvesting and optoelectronics. However, the database of both…

Materials Science · Physics 2022-09-20 Ruo Xi Yang , Matthew K. Horton , Jason Munro , Kristin A. Persson

Superoscillatory wave forms, i.e., waves that locally oscillate faster than their highest Fourier component, possess unusual properties that make them of great interest from quantum mechanics to signal processing. However, the more…

Mathematical Physics · Physics 2016-08-03 Eugene Tang , Lovneesh Garg , Achim Kempf

The optical absorption spectrum of the carbon (4,2) nanotube is computed using an ab-initio many-body approach which takes into account excitonic effects. We develop a new method involving a local basis set which is symmetric with respect…

Materials Science · Physics 2009-11-10 Eric Chang , Giovanni Bussi , Alice Ruini , Elisa Molinari

We study the linear optical properties of helical cylindrical molecular aggregates accounting for the effects of static diagonal disorder. Absorption, linear dichroism, and circular dichroism spectra are presented, calculated using brute…

Disordered Systems and Neural Networks · Physics 2009-11-10 C. Didraga , J. Knoester