Gauge covariances and nonlinear optical responses

Ventura, G. B.; Passos, D. J.; Santos, J. M. B. Lopes dos; Lopes, J. M. Viana Parente; Peres, N. M. R.

doi:10.1103/physrevb.96.035431

Cited by 111 publications

(174 citation statements)

References 20 publications

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“…The response computed with KITE is seen to reproduce the numerically exact results within numerical accuracy Ref. [84].…”

Section: Non-linear Responsementioning

confidence: 55%

“…(2.20). The photogalvanic nonlinear conductivity is nonzero when the photon energy exceeds the gap ( ω ∆ = 7.80 eV) and peaks around 9 eV [84]. The response computed with KITE is seen to reproduce the numerically exact results within numerical accuracy Ref.…”

Section: Non-linear Responsementioning

confidence: 66%

“…The numerical results for the clean system are shown in Fig. 7(b), and compared with numerical results obtained from k-space integration [84]. The physically meaningful symmetrised response (σ yyy (ω, −ω) + σ yyy (−ω, ω))/2 is purely real; see Eq.…”

Section: Non-linear Responsementioning

confidence: 96%

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KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

Anđelković

Covaci

et al. 2020

R. Soc. open sci.

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We present KITE, a general purpose open-source tight-binding software for accurate real-space simulations of electronic structure and quantum transport properties of large-scale molecular and condensed systems with tens of billions of atomic orbitals (N ∼ 10 10 ). KITE's core is written in C++, with a versatile Python-based interface, and is fully optimised for shared memory multi-node CPU architectures, thus scalable, efficient and fast. At the core of KITE is a seamless spectral expansion of lattice Green's functions, which enables large-scale calculations of generic target functions with uniform convergence and fine control over energy resolution. Several functionalities are demonstrated, ranging from simulations of local density of states and photo-emission spectroscopy of disordered materials to large-scale computations of optical conductivity tensors and real-space wave-packet propagation in the presence of magneto-static fields and spin-orbit coupling. On-the-fly calculations of real-space Green's functions are carried out with an efficient domain decomposition technique, allowing KITE to achieve nearly ideal linear scaling in its multi-threading performance. Crystalline defects and disorder, including vacancies, adsorbates and charged impurity centers, can be easily set up with KITE's intuitive interface, paving the way to user-friendly large-scale quantum simulations of equilibrium and nonequilibrium properties of molecules, disordered crystals and heterostructures subject to a variety of perturbations and external conditions. arXiv:1910.05194v1 [cond-mat.mes-hall] 11 Oct 2019 2 IntroductionComputational modelling has become an essential tool in both fundamental and applied research that has propelled the discovery of new materials and their translation into practical applications [1]. The study of condensed phases of matter has benefited from significant advances in electronic structure theory and simulation methodologies. Among these advances are: explicitly correlated wave-function-based techniques achieving sub-chemical accuracy [2], first-principles methods to tackling electronic excitations [3], charge-self-consistent atomistic models for accurate electronic structure calculations [4], and the use of machine learning as means to finding density functionals without solving the Khon-Sham equations [5,6].Semi-empirical atomistic methods are amongst the most simple and effective methods to calculate ground-and excited-state properties of materials [7][8][9][10]. The increasingly popular tight-binding approach [11] has been employed for accurate and fast calculations of total energies and electronic structure in complex materials, including semiconductors [12,13], quantum dots [14] and super-lattices [15,16], and is particularly well-suited for implementation of O(N ) (linear scaling) algorithms for efficient calculations of total energies and forces [17].Accurate tight-binding models have been devised for a plethora of model systems, ranging from metals to ionic materials [18], and shown to correctly p...

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“…The response computed with KITE is seen to reproduce the numerically exact results within numerical accuracy Ref. [84].…”

Section: Non-linear Responsementioning

confidence: 55%

Section: Non-linear Responsementioning

confidence: 66%

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KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

Anđelković

Covaci

et al. 2020

R. Soc. open sci.

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“…with ν representing both the principal and the magnetic quantum numbers of the exciton, the Berry connection [42,43] is given by ξ kvc = −i u k,c |∇ k |u k,v ; V is the volume of the box enclosing the photon field; e is the elementary charge; q,ι is a polarization vector perpendicular to q; a † q,ι is the creation operator of a photon, while [a † q,ι ] † = a q,ι is the annihilation operator of a photon. Note that the approximate equality in Eq.…”

Section: The Spontaneous Radiative Decay Rate Of Excitons In Hbnmentioning

confidence: 99%

Optical absorption of single-layer hexagonal boron nitride in the ultraviolet

Henriques

Ventura

Fernandes

et al. 2019

J. Phys.: Condens. Matter

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In this paper we theoretically describe the absorption of hexagonal boron nitride (hBN) single layer. We develop the necessary formalism and present an efficient method for solving the Wannier equation for excitons. We give predictions for the absorption of hBN on quartz and on graphite. We compare our predictions with recently published results [Elias et al., Nat. Comm. 10, 2639] for a monolayer of hBN on graphite. The spontaneous radiative lifetime of excitons in hBN is also computed. We argue that the optical properties of hBN in the ultraviolet are very useful for the study of peptides and other biomolecules.

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“…However, in practice, the choice of electromagnetic gauge, e.g., the so-called length and velocity * ata@nano.aau.dk gauges, influences the results due to various approximations [32][33][34][35][36][37][38][39][40][41]. Formally, it is straightforward to show that the wave functions in the length and velocity gauges are related via a time-dependent unitary transformation [32].…”

Section: Introductionmentioning

confidence: 99%

Gauge invariance of excitonic linear and nonlinear optical response

Taghizadeh

Pedersen

2018

Phys. Rev. B

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We study the equivalence of four different approaches to calculate the excitonic linear and nonlinear optical response of multiband semiconductors. These four methods derive from two choices of gauge, i.e., length and velocity gauges, and two ways of computing the current density, i.e., direct evaluation and evaluation via the time-derivative of the polarization density. The linear and quadratic response functions are obtained for all methods by employing a perturbative density-matrix approach within the mean-field approximation. The equivalence of all four methods is shown rigorously, when a correct interaction Hamiltonian is employed for the velocity gauge approaches. The correct interaction is written as a series of commutators containing the unperturbed Hamiltonian and position operators, which becomes equivalent to the conventional velocity gauge interaction in the limit of infinite Coulomb screening and infinitely many bands. As a case study, the theory is applied to hexagonal boron nitride monolayers, and the linear and nonlinear optical response found in different approaches are compared.

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Gauge covariances and nonlinear optical responses

Cited by 111 publications

References 20 publications

KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

KITE: high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures

Optical absorption of single-layer hexagonal boron nitride in the ultraviolet

Gauge invariance of excitonic linear and nonlinear optical response

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