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13 pages, 7300 KiB

Open AccessArticle

Strain and Layer Modulations of Optical Absorbance and Complex Photoconductivity of Two-Dimensional InSe: A Study Based on GW0+BSE Calculations

by Chuanghua Yang, Yuan Jiang, Wendeng Huang and Feng Pan

Crystals 2025, 15(7), 666; https://doi.org/10.3390/cryst15070666 - 21 Jul 2025

Viewed by 314

Abstract

Since the definitions of the two-dimensional (2D) optical absorption coefficient and photoconductivity are independent of the thickness of 2D materials, they are more suitable than the dielectric function to describe the optical properties of 2D materials. Based on the many-body GW method and [...] Read more.

Since the definitions of the two-dimensional (2D) optical absorption coefficient and photoconductivity are independent of the thickness of 2D materials, they are more suitable than the dielectric function to describe the optical properties of 2D materials. Based on the many-body GW method and the Bethe–Salpeter equation, we calculated the quasiparticle electronic structure, optical absorbance, and complex photoconductivity of 2D InSe from a single layer (1L) to three layers (3L). The calculation results show that the energy difference between the direct and indirect band gaps in 1L, 2L, and 3L InSe is so small that strain can readily tune its electronic structure. The 2D optical absorbance results calculated taking into account exciton effects show that light absorption increases rapidly near the band gap. Strain modulation of 1L InSe shows that it transforms from an indirect bandgap semiconductor to a direct bandgap semiconductor in the biaxial compressive strain range of −1.66 to −3.60%. The biaxial compressive strain causes a slight blueshift in the energy positions of the first and second absorption peaks in monolayer InSe while inducing a measurable redshift in the energy positions of the third and fourth absorption peaks. Full article

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12 pages, 434 KiB

Open AccessArticle

Hadronic Molecules with Four Charm or Beauty Quarks

by Wen-Ying Liu and Hua-Xing Chen

Universe 2025, 11(2), 36; https://doi.org/10.3390/universe11020036 - 24 Jan 2025

Cited by 4 | Viewed by 739

Abstract

We apply extended local hidden-gauge formalism to study meson–meson interactions with the quark constituents

c c \bar{c} \bar{c}

,

c c \bar{c} \bar{b} / \bar{c} \bar{c} c b

, [...] Read more.

We apply extended local hidden-gauge formalism to study meson–meson interactions with the quark constituents

c c \bar{c} \bar{c}

,

c c \bar{c} \bar{b} / \bar{c} \bar{c} c b

,

c c \bar{b} \bar{b} / \bar{c} \bar{c} b b

,

b b \bar{c} \bar{b} / \bar{b} \bar{b} c b

, and

b b \bar{b} \bar{b}

, in which the exchanged mesons are the fully heavy vector mesons

J / ψ

,

B_{c}^{*}

and

Υ

. We solve the coupled-channel Bethe–Salpeter equation to derive two poles in the

b b \bar{c} \bar{b}

system and two poles in the

c c \bar{c} \bar{b}

system. There are also four charge-conjugated poles in the

\bar{b} \bar{b} c b

and

\bar{c} \bar{c} c b

systems. In the

b b \bar{c} \bar{b}

system, one pole corresponds to a sub-threshold bound state when the cutoff momentum is set to

Λ > 850 MeV

. The other pole in this system corresponds to a sub-threshold bound state when

Λ > 1100 MeV

. In the

c c \bar{c} \bar{b}

system, the two poles correspond to sub-threshold bound states only when

Λ > 1550 MeV

and

Λ > 2650 MeV

. This makes them difficult to identify as deeply bound hadronic molecules. We propose investigating the two poles of the

b b \bar{c} \bar{b}

system in the

μ^{+} μ^{-} B_{c}^{-}

channel at the LHC. Full article

(This article belongs to the Section High Energy Nuclear and Particle Physics)

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15 pages, 4134 KiB

Open AccessArticle

Exploring Epitaxial Structures for Electrically Pumped Perovskite Lasers: A Study of CsPb(Br,I)₃ Based on the Ab Initio Bethe–Salpeter Equation

by Małgorzata Wierzbowska and Juan J. Meléndez

Materials 2024, 17(2), 427; https://doi.org/10.3390/ma17020427 - 15 Jan 2024

Viewed by 1893

Abstract

Halide perovskites are widely used as components of electronic and optoelectronic devices such as solar cells, light-emitting diodes (LEDs), optically pumped lasers, field-effect transistors, photodetectors, and

γ

-detectors. Despite this wide range of applications, the construction of an electrically pumped perovskite laser remains [...] Read more.

Halide perovskites are widely used as components of electronic and optoelectronic devices such as solar cells, light-emitting diodes (LEDs), optically pumped lasers, field-effect transistors, photodetectors, and

γ

-detectors. Despite this wide range of applications, the construction of an electrically pumped perovskite laser remains challenging. In this paper, we numerically justify that mixing two perovskite compounds with different halide elements can lead to optical properties suitable for electrical pumping. As a reference, the chosen model material was CsPbBr

_{3}

, whose performance as a part of lasers has been widely recognised, with some Br atoms substituted by I at specific sites. In particular, a strong enhancement of the low-energy absorption peaks has been obtained using the ab initio Bethe–Salpeter equation. Based on these results, we propose specific architectures of ordered doping that could be realised by epitaxial growth. Efficient light emission from the bottom of the conduction band is expected. Full article

(This article belongs to the Special Issue Advances in Perovskite Solar Cells Research)

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10 pages, 833 KiB

Open AccessArticle

Diquarks and Λ⁰/π⁺, Ξ⁻/π⁺ Ratios in the Framework of the EPNJL Model

by Alexandra Friesen and Yuriy Kalinovsky

Particles 2023, 6(4), 876-885; https://doi.org/10.3390/particles6040056 - 10 Oct 2023

Viewed by 1401

Abstract

The applicability of the effective models to the description of baryons and the behaviour of ratios of strange baryons to pions is discussed. In the framework of the EPNJL model, the Bethe–Salpeter equation is used to find masses of baryons, which are considered [...] Read more.

The applicability of the effective models to the description of baryons and the behaviour of ratios of strange baryons to pions is discussed. In the framework of the EPNJL model, the Bethe–Salpeter equation is used to find masses of baryons, which are considered to be in a diquark-quark state. Baryon melting is discussed at a finite chemical potential, and a flavor dependence of the hadronic deconfinement temperature is pointed out. It is shown that the description of the diquark-quark state at finite chemical potential is limited due to the occurrence of Bose condensate. This effect is strongly manifested in the description of light diquarks and baryons. Both the

Λ^{0} / π^{+}

and

Ξ^{-} / π^{+}

ratios show a sharp behaviour as functions of the

T / μ_{B}

variable, where T and

μ_{B}

are calculated along the melting lines. Full article

(This article belongs to the Special Issue Infinite and Finite Nuclear Matter (INFINUM))

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14 pages, 407 KiB

Open AccessArticle

A Proposal to the ‘12 vs. 32 Puzzle’

by Qiang Li, Wei Feng and Guo-Li Wang

Symmetry 2023, 15(7), 1457; https://doi.org/10.3390/sym15071457 - 21 Jul 2023

Cited by 1 | Viewed by 1316

Abstract

We reconsider the semileptonic decays of

B \to D_{1}^{(')} l {\bar{ν}}_{l}

. The previous theoretical calculations predict a significantly smaller rate for the semileptonic decay of B to [...] Read more.

We reconsider the semileptonic decays of

B \to D_{1}^{(')} l {\bar{ν}}_{l}

. The previous theoretical calculations predict a significantly smaller rate for the semileptonic decay of B to

D_{1}^{'} (J_{l} = \frac{1}{2})

compared with that to the

D_{1} (J_{l} = \frac{3}{2})

, which is not consistent with the current experimental data. This conflict is known as the so-called ‘

\frac{1}{2}

vs.

\frac{3}{2}

puzzle’. In this work, we propose a simple scheme to fix this problem, where we suppose the strong eigenstates

D_{1}^{(')}

that do not coincide with the eigenstate of the weak interaction, since no experimental results show that the weak and the strong interactions have to share the same eigenstates. Within the framework of this tentative scheme, meson B first weakly decays to the weak eigenstates

D_{α (β)}

and then the latter are detected as the

D_{1}^{(')}

by the strong decay products

D^{*} π

. We predict that there exist two new particles

D_{α (β)}

with

J^{P} = 1^{+}

, which were not previously identified. The good performance of the new scheme in describing the experimental data may hint at new symmetry in the weak decays of

B_{q}

to

1^{+}

heavy–light mesons. To test the scheme proposed here, we suggest an experiment to detect the difference in the invariant mass spectra of

D_{1}

that is reconstructed from the B weak decay and from the strong decay products. Full article

(This article belongs to the Section Physics)

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14 pages, 580 KiB

Open AccessArticle

Many-Body Calculations of Excitons in Two-Dimensional GaN

by Yachao Zhang

Crystals 2023, 13(7), 1048; https://doi.org/10.3390/cryst13071048 - 1 Jul 2023

Cited by 2 | Viewed by 3299

Abstract

We present an ab initio study on quasiparticle (QP) excitations and excitonic effects in two-dimensional (2D) GaN based on density-functional theory and many-body perturbation theory. We calculate the QP band structure using

G W

approximation, which generates an indirect band gap of

4.83

[...] Read more.

We present an ab initio study on quasiparticle (QP) excitations and excitonic effects in two-dimensional (2D) GaN based on density-functional theory and many-body perturbation theory. We calculate the QP band structure using

G W

approximation, which generates an indirect band gap of

4.83

eV (

K \to Γ

) for 2D GaN, opening up

1.24

eV with respect to its bulk counterpart. It is shown that the success of plasmon-pole approximation in treating the 2D material benefits considerably from error cancellation. On the other hand, much better gaps, comparable to

G W

ones, could be obtained by correcting the Kohn–Sham gap with a derivative discontinuity of the exchange–correlation functional at much lower computational cost. To evaluate excitonic effects, we solve the Bethe–Salpeter equation (BSE) starting from Kohn–Sham eigenvalues with a scissors operator to open the single-particle gap. This approach yields an exciton binding energy of

1.23

eV in 2D GaN, which is in good agreement with the highly demanding

G W

-BSE results. The enhanced excitonic effects due to reduced dimensionality are discussed by comparing the optical spectra from BSE calculations with that by random-phase approximation (RPA) for both the monolayer and bulk GaN in wurtzite phase. Additionally, we find that the spin–orbit splitting of excitonic peaks is noticeable in 2D GaN but buried in the bulk crystal. Full article

(This article belongs to the Special Issue In Celebration of the 30th Anniversary of Shuji Nakamura’s Contribution to Blue Light-emitting Diodes)

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15 pages, 1247 KiB

Open AccessEditor’s ChoiceArticle

The Key Role of Non-Local Screening in the Environment-Insensitive Exciton Fine Structures of Transition-Metal Dichalcogenide Monolayers

by Wei-Hua Li, Jhen-Dong Lin, Ping-Yuan Lo, Guan-Hao Peng, Ching-Yu Hei, Shao-Yu Chen and Shun-Jen Cheng

Nanomaterials 2023, 13(11), 1739; https://doi.org/10.3390/nano13111739 - 26 May 2023

Cited by 9 | Viewed by 3782

Abstract

In this work, we present a comprehensive theoretical and computational investigation of exciton fine structures of WSe

_{2}

-monolayers, one of the best-known two-dimensional (2D) transition-metal dichalcogenides (TMDs), in various dielectric-layered environments by solving the first-principles-based Bethe–Salpeter equation. While the physical and electronic [...] Read more.

In this work, we present a comprehensive theoretical and computational investigation of exciton fine structures of WSe

_{2}

-monolayers, one of the best-known two-dimensional (2D) transition-metal dichalcogenides (TMDs), in various dielectric-layered environments by solving the first-principles-based Bethe–Salpeter equation. While the physical and electronic properties of atomically thin nanomaterials are normally sensitive to the variation of the surrounding environment, our studies reveal that the influence of the dielectric environment on the exciton fine structures of TMD-MLs is surprisingly limited. We point out that the non-locality of Coulomb screening plays a key role in suppressing the dielectric environment factor and drastically shrinking the fine structure splittings between bright exciton (BX) states and various dark-exciton (DX) states of TMD-MLs. The intriguing non-locality of screening in 2D materials can be manifested by the measurable non-linear correlation between the BX-DX splittings and exciton-binding energies by varying the surrounding dielectric environments. The revealed environment-insensitive exciton fine structures of TMD-ML suggest the robustness of prospective dark-exciton-based optoelectronics against the inevitable variation of the inhomogeneous dielectric environment. Full article

(This article belongs to the Special Issue Excitons and Phonons in Two-Dimensional Materials: From Fundamental to Applications)

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19 pages, 812 KiB

Open AccessArticle

On the η₁(1855), π₁(1400) and π₁(1600) as Dynamically Generated States and Their SU(3) Partners

by Mao-Jun Yan, Jorgivan M. Dias, Adolfo Guevara, Feng-Kun Guo and Bing-Song Zou

Universe 2023, 9(2), 109; https://doi.org/10.3390/universe9020109 - 19 Feb 2023

Cited by 6 | Viewed by 2079

Abstract

In this work, we interpret the newly observed

η_{1} (1855)

resonance with exotic

J^{P C} = 1^{- +}

quantum numbers in the

I = 0

sector, reported by the BESIII Collaboration, as a dynamically generated state from the [...] Read more.

In this work, we interpret the newly observed

η_{1} (1855)

resonance with exotic

J^{P C} = 1^{- +}

quantum numbers in the

I = 0

sector, reported by the BESIII Collaboration, as a dynamically generated state from the interaction between the lightest pseudoscalar mesons and axial-vector mesons. The interaction is derived from the lowest order chiral Lagrangian from which the Weinberg–Tomozawa term is obtained, describing the transition amplitudes among the relevant channels, which are then unitarized using the Bethe–Salpeter equation, according to the chiral unitary approach. We evaluate the

η_{1} (1855)

decays into the

η η^{'}

and

K {\bar{K}}^{*} π

channels and find that the latter has a larger branching fraction. We also investigate its SU(3) partners, and according to our findings, the

π_{1} (1400)

and

π_{1} (1600)

structures may correspond to dynamically generated states, with the former one coupled mostly to the

b_{1} π

component and the latter one coupled to the

K_{1} (1270) \bar{K}

channel. In particular, our result for the ratio

Γ (π_{1} (1600) \to f_{1} (1285) π) / Γ (π_{1} (1600) \to η^{'} π)

is consistent with the measured value, which supports our interpretation for the higher

π_{1}

state. We also report two poles with a mass about 1.7 GeV in the

I = 1 / 2

sector, which may be responsible for the

K^{*} (1680)

. We suggest searching for two additional

η_{1}

exotic mesons with masses around 1.4 and 1.7 GeV. In particular, the predicted

η_{1} (1700)

is expected to have a width around 0.1 GeV and can decay easily into

K \bar{K} π π

. Full article

(This article belongs to the Section High Energy Nuclear and Particle Physics)

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18 pages, 2254 KiB

Open AccessFeature PaperArticle

Electronic and Optical Properties of Alkaline Earth Metal Fluoride Crystals with the Inclusion of Many-Body Effects: A Comparative Study on Rutile MgF₂ and Cubic SrF₂

by Giancarlo Cappellini, Jürgen Furthmüller, Friedhelm Bechstedt and Silvana Botti

Symmetry 2023, 15(2), 539; https://doi.org/10.3390/sym15020539 - 17 Feb 2023

Cited by 5 | Viewed by 2862

Abstract

We conducted a systematic investigation using state-of-the-art techniques on the electronic and optical properties of two crystals of alkaline earth metal fluorides, namely rutile MgF

_{2}

and cubic SrF

_{2}

. For these two crystals of different symmetry, we present density functional theory [...] Read more.

We conducted a systematic investigation using state-of-the-art techniques on the electronic and optical properties of two crystals of alkaline earth metal fluorides, namely rutile MgF

_{2}

and cubic SrF

_{2}

. For these two crystals of different symmetry, we present density functional theory (DFT), many-body perturbation theory (MBPT), and Bethe–Salpeter equation (BSE) calculations. We calculated a variety of properties, namely ground-state energies, band-energy gaps, and optical absorption spectra with the inclusion of excitonic effects. The quantities were obtained with a high degree of convergence regarding all bulk electronic and optical properties. Bulk rutile MgF

_{2}

has distinguished ground-state and excited-state properties with respect to the other cubic fluoride SrF

_{2}

and the other members of the alkaline earth metal fluoride family. The nature of the fundamental gaps and estimates of the self-energy and excitonic effects for the two compounds are presented and discussed in detail. Our results are in good accordance with the measurements and other theoretical–computational data. A comparison is made between the excitation and optical properties of bulk rutile MgF

_{2}

, cubic SrF

_{2}

, and the corresponding clusters, for which calculations have recently been published, confirming strong excitonic effects in finite-sized systems. Full article

(This article belongs to the Special Issue Advances in Optics and Symmetry/Asymmetry)

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35 pages, 1247 KiB

Open AccessReview

Generalised Parton Distributions in Continuum Schwinger Methods: Progresses, Opportunities and Challenges

by Cédric Mezrag

Particles 2023, 6(1), 262-296; https://doi.org/10.3390/particles6010015 - 8 Feb 2023

Cited by 11 | Viewed by 2913

Abstract

This paper review the modelling efforts regarding Generalised Parton Distributions (GPDs) using continuum techniques relying on Dyson–Schwinger and Bethe–Salpeter equations. The definition and main properties of the GPDs are first recalled. Then, we detail the strategies developed in the last decade in the [...] Read more.

This paper review the modelling efforts regarding Generalised Parton Distributions (GPDs) using continuum techniques relying on Dyson–Schwinger and Bethe–Salpeter equations. The definition and main properties of the GPDs are first recalled. Then, we detail the strategies developed in the last decade in the meson sector, highlighting that observables connected to the pion GPDs may be measured at future colliders. We also highlight the challenges one will face when targeting baryons in the future. Full article

(This article belongs to the Special Issue Strong Interactions in the Standard Model: Massless Bosons to Compact Stars)

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10 pages, 2260 KiB

Open AccessArticle

Cluster Formation Effect of Water on Pristine and Defective MoS₂ Monolayers

by Kangli Wang and Beate Paulus

Nanomaterials 2023, 13(2), 229; https://doi.org/10.3390/nano13020229 - 4 Jan 2023

Cited by 2 | Viewed by 1855

Abstract

The structure and electronic properties of the molybdenum disulfide (MoS₂) monolayer upon water cluster adsorption are studied using density functional theory and the optical properties are further analyzed with the Bethe–Salpeter equation (BSE). Our results reveal that the water clusters are [...] Read more.

The structure and electronic properties of the molybdenum disulfide (MoS₂) monolayer upon water cluster adsorption are studied using density functional theory and the optical properties are further analyzed with the Bethe–Salpeter equation (BSE). Our results reveal that the water clusters are electron acceptors, and the acceptor tendency tends to increase with the size of the water cluster. The electronic band gap of both pristine and defective MoS₂ is rather insensitive to water cluster adsorbates, as all the clusters are weakly bound to the MoS₂ surface. However, our calculations on the BSE level show that the adsorption of the water cluster can dramatically redshift the optical absorption for both pristine and defective MoS₂ monolayers. The binding energy of the excitons of MoS₂ is greatly enhanced with the increasing size of the water cluster and finally converges to a value of approximately 1.16 eV and 1.09 eV for the pristine and defective MoS₂ monolayers, respectively. This illustrates that the presence of the water cluster could localize the excitons of MoS₂, thereby greatly enhance the excitonic binding energy. Full article

(This article belongs to the Special Issue Graphene and Related 2D Materials)

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14 pages, 1721 KiB

Open AccessArticle

A Density-Functional Theory Study of Hole and Defect-Bound Exciton Polarons in Lithium Niobate

by Falko Schmidt, Agnieszka L. Kozub, Uwe Gerstmann, Wolf Gero Schmidt and Arno Schindlmayr

Crystals 2022, 12(11), 1586; https://doi.org/10.3390/cryst12111586 - 7 Nov 2022

Cited by 4 | Viewed by 3127

Abstract

Hole polarons and defect-bound exciton polarons in lithium niobate are investigated by means of density-functional theory, where the localization of the holes is achieved by applying the

+ U

approach to the oxygen

2 p

orbitals. We find three principal configurations of hole [...] Read more.

Hole polarons and defect-bound exciton polarons in lithium niobate are investigated by means of density-functional theory, where the localization of the holes is achieved by applying the

+ U

approach to the oxygen

2 p

orbitals. We find three principal configurations of hole polarons: (i) self-trapped holes localized at displaced regular oxygen atoms and (ii) two other configurations bound to a lithium vacancy either at a threefold coordinated oxygen atom above or at a two-fold coordinated oxygen atom below the defect. The latter is the most stable and is in excellent quantitative agreement with measured g factors from electron paramagnetic resonance. Due to the absence of mid-gap states, none of these hole polarons can explain the broad optical absorption centered between 2.5 and 2.8 eV that is observed in transient absorption spectroscopy, but such states appear if a free electron polaron is trapped at the same lithium vacancy as the bound hole polaron, resulting in an exciton polaron. The dielectric function calculated by solving the Bethe–Salpeter equation indeed yields an optical peak at

2.6

eV in agreement with the two-photon experiments. The coexistence of hole and exciton polarons, which are simultaneously created in optical excitations, thus satisfactorily explains the reported experimental data. Full article

(This article belongs to the Special Issue Ferroelectrics)

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13 pages, 2710 KiB

Open AccessArticle

Electronic and Optical Properties of Rocksalt Mg_1−xZn_xO and Wurtzite Zn_1−xMg_xO with Varied Concentrations of Magnesium and Zinc

by Yin-Pai Lin, Sergei Piskunov, Laima Trinkler, Mitch Ming-Chi Chou and Liuwen Chang

Materials 2022, 15(21), 7689; https://doi.org/10.3390/ma15217689 - 1 Nov 2022

Cited by 2 | Viewed by 1993

Abstract

The structural, electronic and optical properties of rocksalt Mg

_{1 - x}

Zn

_{x}

O and wurtzite Zn

_{1 - x}

Mg

_{x}

O with the concentration of Zn and Mg varying from 0.125 to 0.875 were investigated using density functional theory (DFT), [...] Read more.

The structural, electronic and optical properties of rocksalt Mg

_{1 - x}

Zn

_{x}

O and wurtzite Zn

_{1 - x}

Mg

_{x}

O with the concentration of Zn and Mg varying from 0.125 to 0.875 were investigated using density functional theory (DFT), DFT+U, linear response theory and the Bethe–Salpeter equation. According to the experimental band gap for varied concentrations of magnesium and zinc, modeling the supercell was utilized for the varied concentrations of Mg/Zn/O compounds in order to not only avoid constructing the complicated interface systems that are observed in the experiments but also take into account the excitonic effects that usually require huge computational resources. From the calculated density of states, the Zn states are highly related to the edge of the conduction band minimum and responsible for the width of bandgap. In addition, the contribution of Zn–d states is below expectations as they are located away from the VBM. As for the optical response, an increase in Zn concentration would cause a red-shifted spectrum, on the whole. In contrast, the higher concentration of Mg also triggers the blue-shift of the optical spectrum. In addition, anisotropic properties could be found in the spectrum with consideration of the excitonic effects, whereas there is no apparent difference in optical response based on linear response theory. In addition, the optical features of this work reflect the characteristic peaks of the literature around the absorption onset. Full article

(This article belongs to the Special Issue Frontiers in Synthesis of Zinc Oxides: Experimental and Theoretical Approach)

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15 pages, 959 KiB

Open AccessEditor’s ChoiceArticle

Ab-Initio Study of Calcium Fluoride Doped with Heavy Isotopes

by Martin Pimon, Andreas Grüneis, Peter Mohn and Thorsten Schumm

Crystals 2022, 12(8), 1128; https://doi.org/10.3390/cryst12081128 - 11 Aug 2022

Cited by 5 | Viewed by 2702

Abstract

Precision laser spectroscopy of the 229-thorium nuclear isomer transition in a solid-state environment would represent a significant milestone in the field of metrology, opening the door to the realization of a nuclear clock. Working toward this goal, experimental methods require knowledge of various [...] Read more.

Precision laser spectroscopy of the 229-thorium nuclear isomer transition in a solid-state environment would represent a significant milestone in the field of metrology, opening the door to the realization of a nuclear clock. Working toward this goal, experimental methods require knowledge of various properties of a large band-gap material, such as calcium fluoride doped with specific isotopes of the heavy elements thorium, actinium, cerium, neptunium, and uranium. By accurately determining the atomic structure of potential charge compensation schemes by using a generalized gradient approximation within the ab-initio framework of density functional theory, calculations of electric field gradients on the dopants become accessible, which cause a quadrupole splitting of the nuclear-level structure that can be probed experimentally. Band gaps and absorption coefficients in the range of the 229-thorium nuclear transition are estimated by using the

G_{0} W_{0}

method and by solving the Bethe–Salpeter equation. Full article

(This article belongs to the Special Issue Defects in Crystals)

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9 pages, 2408 KiB

Open AccessArticle

Versatile Gold Telluride Iodide Monolayer as a Potential Photocatalyst for Water Splitting

by Bingru Hai, Zhanying Yang, Bo Zhou, Lei Zhang, Aijun Du and Chunmei Zhang

Nanomaterials 2022, 12(11), 1915; https://doi.org/10.3390/nano12111915 - 3 Jun 2022

Cited by 4 | Viewed by 2366

Abstract

Two-dimensional materials promise great potential for photochemical water splitting due to the abundant active sites and large surface area, but few of the known materials meet the rigorous requirements. In this work, we systematically investigate structural, electronic, and optical properties of an experimentally [...] Read more.

Two-dimensional materials promise great potential for photochemical water splitting due to the abundant active sites and large surface area, but few of the known materials meet the rigorous requirements. In this work, we systematically investigate structural, electronic, and optical properties of an experimentally unexplored 2D material, i.e., gold telluride iodide (AuTeI) monolayer using density functional theory and Bethe–Salpeter equation approaches. Bulk AuTeI is a layered material and was realized in experiments a few decades ago. However, its bandgap is relatively small for water splitting. We find the exfoliation of monolayer AuTeI from the bulk phase is highly favorable, and 2D AuTeI is dynamically stable. The bandgap of 2D AuTeI becomes larger due to the quantum confinement effect. Importantly, the edge positions of the conduction band minimum and valence band maximum of 2D AuTeI perfectly fit the water oxidation and reduction potentials, enabling it a promising photocatalyst for water splitting. Additionally, the exciton binding energy of 2D AuTeI is calculated to be 0.35 eV, suggesting efficient electron-hole separation. Our results highlight a new and experimentally accessible 2D material for potential application in photocatalytic water splitting. Full article

(This article belongs to the Special Issue Optical Properties of Semiconductor Nanomaterials)

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