Excitons in nonlinear optical responses: shift current in MoS2 and GeS monolayers

npj Computational Materials, Journal Year: 2025, Volume and Issue: 11(1)

Published: Jan. 13, 2025

It is well-known that exciton effects are determinant to understanding the optical absorption spectrum of low-dimensional materials. However, role excitons in nonlinear responses has been much less investigated at experimental level. Additionally, computational methods calculate conductivities real materials still not widespread, particularly taking into account excitonic interactions. We present a methodology second-order 2D relying on: (i) ab initio tight-binding Hamiltonians obtained by Wannier interpolation and (ii) solving Bethe-Salpeter equation with effective electron-hole Here, particular, we explore shift current monolayer Focusing on MoS2 GeS systems, our results show 2p-like excitons, which dark linear response regime, yield contribution photocurrent comparable 1s-like excitons. Under radiation intensity ~104W/cm2, theory predicts in-gap photogalvanic currents almost ~10 nA sufficiently clean samples, typically one order magnitude higher than value predicted independent-particle near band edge.

Language: Английский

---

Critical assessment of G0W0 calculations for 2D materials: the example of monolayer MoS2

npj Computational Materials, Journal Year: 2024, Volume and Issue: 10(1)

Published: April 18, 2024

Two-dimensional (2D) materials combine many fascinating properties that make them more interesting than their three-dimensional counterparts for a variety of applications. For example, 2D exhibit stronger electron-phonon and electron-hole interactions, energy gaps effective carrier masses can be easily tuned. Surprisingly, published band several obtained with the $GW$ approach, state-of-the-art in electronic-structure calculations, are quite scattered. The details these such as underlying geometry, starting point, inclusion spin-orbit coupling, treatment Coulomb potential critically determine how accurate results are. Taking monolayer MoS$_2$ representative material, we employ linearized augmented planewave + local orbital method to systematically investigate all aspects affect quality $G_0W_0$ also provide summary literature data. We conclude best overall agreement experiments coupled-cluster calculations is found HSE06 point including truncated potential, an analytical singularity at $q=0$.

Language: Английский

---

Nonempirical dielectric dependent hybrid as an accurate starting point for the single shot G0W0 calculation of chalcopyrite semiconductors

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(6)

Published: Feb. 10, 2025

The accuracy of quasiparticle corrections in a single-shot G0W0 calculation relies heavily on the preceding eigensystem density functional theory (DFT). An incorrect energy spectrum obtained from DFT can result an inaccurate bandgap. This study explicitly investigates bandgaps chalcopyrite semiconductors within G0W0, considering various approximations, including semilocal, hybrid, and nonempirical screened dielectric-dependent hybrid (DDH) as starting point for calculation. superiority top DDH is evident achieving highly accurate semiconductors. In addition, when Bethe–Salpeter equation solved, optical absorption spectra derived these calculations are remarkably precise. demonstrates that G0W0@DDH serves cost-effective precise tool applications related to semiconductors, particularly cases where self-consistent GW (scGW) challenging.

Language: Английский

---

Low-Scaling GW Algorithm Applied to Twisted Transition-Metal Dichalcogenide Heterobilayers

Journal of Chemical Theory and Computation, Journal Year: 2024, Volume and Issue: 20(5), P. 2202 - 2208

Published: Feb. 14, 2024

The GW method is widely used for calculating the electronic band structure of materials. high computational cost algorithms prohibits their application to many systems interest. We present a periodic, low-scaling, and highly efficient algorithm that benefits from locality Gaussian basis polarizability. enables G0W0 calculations on MoSe2/WS2 bilayer with 984 atoms per unit cell, in 42 h using 1536 cores. This 4 orders magnitude faster than plane-wave algorithm, allowing unprecedented studies excitations at nanoscale.

Language: Английский

---

Optical absorption spectra of metal oxides from time-dependent density functional theory and many-body perturbation theory based on optimally-tuned hybrid functionals

Physical Review Materials, Journal Year: 2023, Volume and Issue: 7(12)

Published: Dec. 5, 2023

Using both time-dependent density functional theory (TDDFT) and the ``single-shot'' GW plus Bethe-Salpeter equation (GW-BSE) approach, we compute optical band gaps absorption spectra from first principles for eight common binary ternary closed-shell metal oxides (MgO, ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$, CaO, ${\mathrm{TiO}}_{2}, {\mathrm{Cu}}_{2}\mathrm{O}$, ZnO, ${\mathrm{BaSnO}}_{3}$, ${\mathrm{BiVO}}_{4}$), based on nonempirical Wannier-localization-based, optimally tuned, screened range-separated hybrid functional. Overall, find excellent agreement between our TDDFT GW-BSE results experiment, with a mean absolute error smaller than 0.4 eV, including ${\mathrm{Cu}}_{2}\mathrm{O}$ ZnO that are traditionally considered to be challenging methods.

Language: Английский

---

Accurate and efficient prediction of the band gaps and optical spectra of chalcopyrite semiconductors from a nonempirical range-separated dielectric-dependent hybrid: Comparison with many-body perturbation theory

Physical review. B./Physical review. B, Journal Year: 2024, Volume and Issue: 109(4)

Published: Jan. 17, 2024

The accurate prediction of electronic and optical properties in chalcopyrite semiconductors has been a persistent challenge for density functional theory (DFT) based approaches. Addressing this issue, we demonstrate that very results can be obtained using non-empirical screened dielectric-dependent hybrid (DDH) functional. This novel approach showcases its impressive capability to accurately determine band gaps, bowing parameters, absorption spectra systems. What sets the DDH apart is adeptness capturing many-body physics associated with highly localized $d$ electrons. Notably, accuracy comparable perturbation methods (such as $G_0W_0$ or various approximations gaps Bethe-Salpeter equation (BSE) on top spectra) less computational cost, ensuring more accessible application across research domains. present show predictive power functional, pointing toward promising applications where efficiency are crucial considerations. Overall, offers compelling balance between cost-effectiveness precision, making it valuable tool future endeavors exploring beyond.

Language: Английский

---

Core-hole induced misalignment between Van Hove singularities and K -edge fine structure in carbon nanotubes

Physical Review Research, Journal Year: 2025, Volume and Issue: 7(1)

Published: Feb. 18, 2025

We investigate the relationship between -edge fine structure of isolated single-wall carbon nanotubes (SWCNTs) and Van Hove singularities (VHSs) in conduction-band density states. To this end, we model x-ray absorption spectra SWCNTs using final-state approximation Bethe-Salpeter equation (BSE) method. Both methods can reproduce experimental structure, where BSE results improve on peak positions amplitude rations compared to approximation. When modeled is related VHSs, significant differences are found. suggest that these arise due modifications core exciton wave functions induced by confinement along circumference. Additionally, analyze character excitons SWCNTs, find first bright Frenkel excitons, while higher-lying charge resonance Finally, qualitative picture based VHSs states holds when there a large energy gap successive VHSs. Published American Physical Society 2025

Language: Английский

---

Resolving contradictory estimates of band gaps of bulk PdSe2: A Wannier-localized optimally-tuned screened range-separated hybrid density functional theory study

Applied Physics Letters, Journal Year: 2025, Volume and Issue: 126(14)

Published: April 1, 2025

Palladium diselenide (PdSe2)—a layered van der Waals material—is attracting significant attention for optoelectronics due to the wide tunability of its band gap from infrared through visible range as a function number layers. However, there continues be disagreement over precise nature and value optical bulk PdSe2, owing rather small this that complicates experimental measurements their interpretation. Here, we design employ Wannier-localized optimally tuned screened range-separated hybrid (WOT-SRSH) functional investigate electronic structures absorption spectra monolayer PdSe2. In particular, account carefully finite exciton center-of-mass momentum within time-dependent WOT-SRSH framework calculate indirect onset accurately. Our results agree well with best available photoconductivity measurements, state-of-the-art many-body perturbation theory calculations, confirming PdSe2 has an in mid-infrared (upper bound 0.44 eV). More generally, work further bolsters utility approach predictive modeling semiconductors.

Language: Английский

---

Finite-momentum dielectric function and excitonic effects from time-dependent density-functional theory with dielectrically screened hybrid functionals

Physical review. B./Physical review. B, Journal Year: 2025, Volume and Issue: 111(15)

Published: April 11, 2025

Language: Английский

---

Stability of the Long-Range Corrected Exchange-Correlation Functional and the Proca Procedural Functional in Time-Dependent Density-Functional Theory

Journal of Chemical Theory and Computation, Journal Year: 2025, Volume and Issue: unknown

Published: April 24, 2025

Excitonic effects in the optical absorption spectra of solids can be described with time-dependent density-functional theory (TDDFT) linear-response regime, using a simple class approximate, long-range corrected (LRC) exchange-correlation functionals. It was recently demonstrated that LRC approximation also employed real-time TDDFT to describe exciton dynamics. Here, we investigate numerical stability approach two-dimensional model solid. is found Kohn-Sham equation an vector potential becomes more and prone instabilities for increasing binding energies. The origin these traced back time-averaged violations zero-force theorem, which leads robust stabilization scheme. This explains justifies proposed method by Dewhurst, J. K. [ Phys. Rev. B 2025, 111, L060302] stabilize potential, known as Proca procedural functional.

Language: Английский

---