Second-order Nonlinear Optical Response Research Articles

DFT Study on the Second-Order NLO Responses of 2-Phenyl Benzoquinoline Ir(III) Complexes by Substituents and Redox Effects.

Metal complexes have received extensive attention in nonlinear optical (NLO) materials because of their advantages, such as shorter response times and more flexible structural properties. Density functional theory is used in investigating the geometric structures, electronic structures, charge centroid, and first hyperpolarizability (βtot) of a series of selected 15 coordinated Ir(III) complexes. The substitute effect and one-electron redox process effects on the structures and properties of 15 coordinated Ir(III) complexes are considered. When the electron-withdrawing group is introduced into the ligand, the HOMO-LUMO energy gap decreases and the βtot value increases, positively correlating with the electron-withdrawing ability. The single electron redox process can also improve the NLO responses of complexes, especially the reduction process. The βtot value of complex 4- is the largest, 2078 times higher than that of complex 4. The analysis shows that the variation of NLO responses of complexes is ascribed to the change of electronic structures and the charge transfer modes induced by the ligand modification and redox process, which are considered to be two effective methods in enhancing the NLO responses of 2-phenyl benzoquinoline Ir(III) complexes. This study aims to offer design insights into high-performance nonlinear optical materials.

Harnessing complexity: Nonlinear optical phenomena in L-shapes, nanocrescents, and split-ring resonators.

We conduct systematic studies of the optical characteristics of plasmonic nanoparticles that exhibit C2v symmetry. In particular, we analyze three distinct geometric configurations: an L-type shape, a crescent, and a split-ring resonator shaped like the Greek letter π. Optical properties are examined using the finite-difference time-domain method. It is demonstrated that all three shapes exhibit two prominent plasmon modes associated with the two axes of symmetry. This is in addition to a wide range of resonances observed at high frequencies corresponding to quadrupole modes and peaks due to sharp corners. Next, to facilitate nonlinear analysis, we employ a semiclassical hydrodynamic model, where the electron pressure term is explicitly accounted for. This model goes beyond the standard Drude description and enables capturing nonlocal and nonlinear effects. Employing this model enables us to rigorously examine the second-order angular resolved nonlinear optical response of these nanoparticles in each of the three configurations. Two pumping regimes are considered, namely, continuous wave (CW) and pulsed excitations. For CW pumping, we explore the properties of the second harmonic generation (SHG). Polarization and angle-resolved SHG spectra are obtained, revealing strong dependence on the nanoparticle geometry and incident wave polarization. The C2v symmetry is shown to play a key role in determining the polarization states and selection rules of the SHG signal. For pulsed excitations, we discuss the phenomenon of broadband terahertz (THz) generation induced by the difference-frequency generation . It is shown that the THz emission spectra exhibit unique features attributed to the plasmonic resonances and symmetry of the nanoparticles. The polarization of the generated THz waves is also examined, revealing interesting patterns tied to the nanoparticle geometry. To gain deeper insight, we propose an analytical theory that agrees very well with the numerical experiments. The theory shows that the physical origin of the THz radiation is the mixing of various frequency components of the fundamental pulse by the second-order nonlinear susceptibility. An expression for the far-field THz intensity is derived in terms of the incident pulse parameters and the nonlinear response tensor of the nanoparticle. The results presented in this work offer new insights into the linear and nonlinear optical properties of nanoparticles with C2v symmetry. The demonstrated strong SHG response and efficient broadband THz generation hold great promise for applications in nonlinear spectroscopy, nanophotonics, and optoelectronics. The proposed theoretical framework also provides a valuable tool for understanding and predicting the nonlinear behavior of other related nanostructures.

Giant nonlinear optical response of fullerene polymer fragments: a DFT perspective

Organic π-conjugated materials exhibit exceptional nonlinear optical (NLO) properties due to their unique electronic structures, characterized by short response times and large NLO responses. Fullerene (C60) is one of the few polymer species that possess a rich π-conjugated system, making it a promising material with significant NLO responses. In the present paper, we designed three C60 polymer fragments and employed density functional theory to estimate their molecular static first and second hyperpolarizabilities. Compared to previously reported fullerene derivatives, the designed C60 polymer fragments can exhibit notable second-order and third-order molecular NLO responses. The study shows that the hyperpolarizabilities and energy gaps of the investigated C60 polymer fragments are greatly influenced by their topological structures and bonding modes. These findings provide new insights for the design of novel NLO materials based on C60 polymers, and the realization of tunable NLO responses in C60 cluster-based molecular systems, which may have significant applications in nanophotonic devices.

Role of cation nature in crown ether appended 25-Oxasmaragdyrins with second-order NLO responses: As potential and selective metal ions detector

Crown ethers, known for their efficacy as metal ion traps, have garnered significant interest in optoelectronic applications due to their unique cavity structure and special binding ability with metals. Herein, we systematically designed and investigated the second-order nonlinear optical (NLO) properties of an intriguing compound, 18-crown-6 derivative appended with 25-oxasmaragdyrins (Cr-Prs), achieved through the incorporation of diverse metal ions into the crown ether ring. Significantly, the βtot values of compounds with alkaline earth metal ions (Mg2+, Ca2+) are greater than those compounds with alkali metal ions (Na+, K+). Interestingly, the Hg2+@Cr-Prs compound exhibits a tremendous second-order NLO property with the βtot value of 5.34 × 105 au. Further insights into substantial βtot values across all compounds were provided through a comprehensive analysis of the transition energies, the molecular orbitals, and the absorption spectra of the main excited states. The calculation results conclude that the second-order NLO properties of Cr-Prs can be modulated by incorporating metal ions into the crown ether ring. Crown ether emerges as a facilitator in detecting and identifying Hg2+ ions, serving as an effective NLO-based ion detector. These findings not only broaden the scope of cation detection and efficiency but also present innovative applications in analytical and optoelectronic research, encapsulating the essence of our study within a concise framework.

Intense second-harmonic generation in two-dimensional PtSe2

Abstract Platinum diselenide (PtSe2), classified as a noble metal dichalcogenide, has garnered substantial interest owing to its layer-dependent band structure, remarkable air-stability, and high charge-carrier mobilities. These properties make it highly promising for a wide array of applications in next-generation electronic and optoelectronic devices, as well as sensors. Additionally, two-dimensional (2D) PtSe2 demonstrates significant potential as a saturable absorber due to its exceptional nonlinear optical response across an ultrabroad spectra range, presenting exciting opportunities in ultrafast and nonlinear photonics. In this work, we explore the second-order nonlinear optical characteristics of 2D PtSe2 by analyzing its second-harmonic generation (SHG) excited by a pulsed laser at 1064 nm. Our investigation unveils a layer-dependent SHG response in PtSe2, with prominent SHG intensity observed in few-layer PtSe2. The distinct six-fold polarization dependence pattern observed in the SHG intensity reflects the inherent threefold rotational symmetry inherent to the PtSe2 crystal structure. Remarkably, the SHG intensity of 4-layer PtSe2 surpasses that of mechanically exfoliated monolayer molybdenum disulfide (MoS2) by approximately two orders of magnitude (60-fold), underscoring its exceptional second-order nonlinear optical response. Combined with its ultrahigh air-stability, these distinctive nonlinear optical characteristics position two-dimensional PtSe2 as a promising candidate for ultrathin nonlinear nanophotonic devices.

Variable-Angle Surface Spectroscopy Reveals the Water Structure in the Stern Layer at Charged Aqueous Interfaces.

At charged aqueous interfaces, the second-order nonlinear optical response originates from water molecules within the diffuse part of the electrical double layer, which are ordered by the surface field and from water that additionally experiences chemical and physical interactions with the surface in the Stern layer. These two environments can either reinforce or diminish the overall signal and can be disentangled by varying the coherence length of their interaction with external laser fields. Here, we demonstrate a method in which the angle of incidence is varied to afford a significant change in the coherence length. When this technique was applied to the silica-water interface, it was observed that water molecules in the Stern and diffuse layers direct their hydrogen atoms toward the mineral surface at a low ionic strength and neutral pH. A decrease in the signal with increasing ionic strength is attributed to hydrated cation adsorption that competes with free water for deprotonated silanol sites.

A computational study on the second-order nonlinear optical response of a new unsymmetrical oxovanadium complex

A new unsymmetrical N2O2 Schiff base oxovanadium (IV) complex, VOLPy, was synthesized with excellent yield and characterized using conventional methods. The crystal structure of the VOLPy complex was determined through X-ray diffraction, revealing a distorted square pyramidal coordination configuration around the central vanadium ion. The solid-state structure is stabilized by various non-covalent short contacts, generating complex 3D supramolecular network. The electrochemical properties of the VOLPy complex were investigated in different media, demonstrating diffusion-controlled reversible or quasi-reversible processes within the potential range of 200–1000 mV, involving a single electron VV/VIV reduction. The diffusion coefficients were calculated using Levich plots Ilim = f(ω1/2). Using quantum calculations at the CAM-B3LYP level with a 6-311G**/LanL2DZ basis set, we systematically assessed various structural parameters, electronic properties, linear and nonlinear optical responses at static and dynamic regimes for oxovanadium complexes, V(V)OL and V(IV)OL, in both gaseous and solvent environments. The results reveal a robust alignment between quantum calculations and experimental data, with only minor deviations. This study anticipates that these specifically designated complexes hold substantial potential as excellent candidates for second-order nonlinear optical (NLO) materials.

Side-Chain Type Ferrocene Macrocycles.

A class of side-chain type ferrocene macrocycles with a radially conjugated system is introduced in this study. The stereo configurations of these ferrocene rings were determined through single-crystal X-ray diffraction analysis. Notably, in the solid state, the ferrocene rings exhibit a distinctive herringbone stacking pattern imposed by a ferrocene-to-ring host-guest interaction. Through UV-vis absorption spectroscopy, electrochemical measurements, and theoretical calculations, valuable insights into the electronic properties of these rings were obtained. In addition, the single crystal of macrocycle A 2 B demonstrates a second-order nonlinear optical response. As a class of organometallic nanorings, this work holds great potential for further exploration in the fields of organometallic chemistry, molecular electronics, and host-guest chemistry.

Third Harmonic Generation in Thin NbOI2 and TaOI2.

The niobium oxide dihalides have recently been identified as a new class of van der Waals materials exhibiting exceptionally large second-order nonlinear optical responses and robust in-plane ferroelectricity. In contrast to second-order nonlinear processes, third-order optical nonlinearities can arise irrespective of whether a crystal lattice is centrosymmetric. Here, we report third harmonic generation (THG) in two-dimensional (2D) transition metal oxide iodides, namely NbOI2 and TaOI2. We observe a comparable THG intensity from both materials. By benchmarking against THG from monolayer WS2, we deduce that the third-order susceptibility is approximately on the same order. THG resonances are revealed at different excitation wavelengths, likely due to enhancement by excitonic states and band edge resonances. The THG intensity increases for material thicknesses up to 30 nm, owing to weak interlayer coupling. After this threshold, it shows saturation or a decrease, due to optical interference effects. Our results establish niobium and tantalum oxide iodides as promising 2D materials for third-order nonlinear optics, with intrinsic in-plane ferroelectricity and thickness-tunable nonlinear efficiency.

Control of Polar/Antipolar Layered Organic Semiconductors by the Odd-Even Effect of Alkyl Chain.

Some rodlike organic molecules exhibit exceptionally high layered crystallinity when composed of a link between π-conjugated backbone (head) and alkyl chain (tail). These molecules are aligned side-by-side unidirectionally to form self-organized polar monomolecular layers, providing promising 2D materials and devices. However, their interlayer stacking arrangements have never been tunable, preventing the unidirectional arrangements of molecules in whole crystals. Here, it is demonstrated that polar/antipolar interlayer stacking can be systematically controlled by the alkyl carbon number n, when the molecules are designed to involve effectively weakened head-to-head affinity. They exhibit remarkable odd-even effect in the interlayer stacking: alternating head-to-head and tail-to-tail (antipolar) arrangement in odd-n crystals, and uniform head-to-tail (polar) arrangement in even-n crystals. The films show excellent field-effect transistor characteristics presenting unique polar/antipolar dependence and considerably improved subthreshold swing in the polar films. Additionally, the polar films present enhanced second-order nonlinear optical response along normal to the film plane. These findings are key for creating polarity-controlled optoelectronic materials and devices.

Dynamic effects on the nonlinear optical properties of donor acceptor stenhouse adducts: insights from combined MD + QM simulations.

The second-order nonlinear optical (NLO) responses of a donor-acceptor stenhouse adduct (DASA) are investigated by using a computational approach combining molecular dynamics simulations and density functional theory (DFT) calculations. Specific force fields for the open and closed photoswitching forms are first parameterized and validated according to the Joyce protocol, in order to finely reproduce the geometrical features and potential energy surfaces of both isomers in chloroform solution. Then, DFT calculations are performed on structural snapshots extracted at regular time steps of the MD trajectories to address the influence of the thermalized conformational dynamics on the NLO responses related to hyper-Rayleigh scattering (HRS) experiments. We show that accounting for the structural dynamics largely enhances the HRS hyperpolarizability (βHRS) compared to DFT calculations considering solely equilibrium geometries, and greatly improves the agreement with experimental measurements. Furthermore, we show that the NLO responses of the NLO-active open form are correlated with the bond order alternation along the triene bridge connecting the donor and acceptor moieties, which is rationalized using simple essential state models.

Modulation of the NLO properties of p-coumaric acid by the solvent effects and proton dissociation

Solute-solvent interactions and deprotonation effects have been related to second-order nonlinear optical response modulators. This work takes advantage of sequential Monte Carlo/Quantum mechanics together with Time-Dependent Density Functional Theory, Coupled Cluster methods, and the hyper-Rayleigh scattering formalism to investigate how these effects influence the stability and optical response of p-coumaric acid (pCA) and its anionic and diionic forms. The solvent influences the chromophores in different ways, inducing bathochromic and hypsochromic solvatochromism so for the neutral pCA molecule as for its deprotonated derivatives. The results indicate a high sensitivity of the nonlinear optics (NLO) parameters with relation to proton dissociation. Ionization of the carboxyl group produces the lowest values of the first frequency-dependent hyperpolarizability (βHRS), while phenolic deprotonation leads to the highest values. The results show that proton removal can be used as a switch that modulates the NLO response within a wide range of values (159.15≤βHRS≤4393.97 au) greater than those reported for reference NLO chromophores like urea (37.3 au) and p-nitroaniline (74.3 au). Thermochemical analysis of enthalpies and Gibbs free energies indicate that both monoionic forms of the pCA molecule are the most stable in gas or water solvents. Furthermore, these structures represent the limits of NLO modulation in the gas and solvent phases. Analysis of the projected density of states and mapping of the molecular electrostatic potential indicate that increased contributions from conduction electrons found in the aromatic ring are the mechanism by which deprotonation enhances the NLO response. All the results show that ionic pCA forms are promising in the functionalization of optoelectronic devices.

Effect of charge transfer on the first hyper-polarizability of N,N-dimethylaniline and julolidine: a DFT based comparative study.

Quantum mechanical calculations involving electron correlation, frequency dispersion, and solvent effects were carried out to examine the second-order nonlinear optical response ofvarious acceptor, X (-CF3, -CN, -NO2) substituted in N,N-dimethylaniline (DMA) and julolidine(JLD). Here, both DMA and JLD acts as donor and the three substituted groups, X (-CF3, -CNand -NO2) at the para position of both the ring systems as acceptor. The NLO response (βHRS) of -CF3 and -CN substituted DMA and JLD is relatively lower compared to DMA-NO2 andJLD-NO2. The charge distribution is found higher in case of -NO2substituted DMA and JLD (±443 and ±449) compared to their -CF3 or -CN substitution. Electronic characteristics such asUV-Vis absorption spectra, crucial excited state parameters and charge transfer contribution to βHRS have been used to explain the NLO parameter of DMA-X and JLD-X. Variation of theincident optical frequency of light shows fluctuation of βHRS value and highest values of βHRS are obtain at the λmax frequency of each compound. Solvent polarity variation study on βHRSshows that βHRS varies linearly with the Kirkwood-Onsagar dielectric factor (D). All computational studies have been carried out using density functional theory (DFT) based method. Since CAM-B3LYP based hybrid functional improves the asymptotic behavior of theexchange interaction by dividing into short-range and long-range components, first hyperpolarizability values in the present study were computed using DFT/ CAM-B3LYP/ 6-31G+(d,p) level oftheory.

Design of High-Performance Organic Nonlinear Optical and Terahertz Crystals by Controlling the van der Waals Volume.

In the development of new organic crystals for nonlinear optical and terahertz (THz) applications, it is very challenging to achieve the essentially required non-centrosymmetric molecular arrangement. Moreover, the resulting crystal structure is mostly unpredictable due to highly dipolar molecular components with complex functional substituents. In this work, new organic salt crystals with top-level macroscopic optical nonlinearity by controlling the van der Waals volume (VvdW ), rather than by trial and error, are logically designed. When the VvdW of molecular ionic components varies, the corresponding crystal symmetry shows an observable trend: change from centrosymmetric to non-centrosymmetric and back to centrosymmetric. All non-centrosymmetric crystals exhibit an isomorphic P1 crystal structure with an excellent macroscopic second-order nonlinear optical response. Apart from the top-level macroscopic optical nonlinearity, new organic crystals introducing highly electronegative fluorinated substituents with strong secondary bonding ability show excellent performance in efficient and broadband THz wave generation, high crystal density, high thermal stability, and good bulk crystal growth ability.

Manipulation of nonlinear optical responses in layered ferroelectric niobium oxide dihalides

Realization of highly tunable second-order nonlinear optical responses, e.g., second-harmonic generation and bulk photovoltaic effect, is critical for developing modern optical and optoelectronic devices. Recently, the van der Waals niobium oxide dihalides are discovered to exhibit unusually large second-harmonic generation. However, the physical origin and possible tunability of nonlinear optical responses in these materials remain to be unclear. In this article, we reveal that the large second-harmonic generation in NbOX2 (X = Cl, Br, and I) may be partially contributed by the large band nesting effect in different Brillouin zone. Interestingly, the NbOCl2 can exhibit dramatically different strain-dependent bulk photovoltaic effect under different polarized light, originating from the light-polarization-dependent orbital transitions. Importantly, we achieve a reversible ferroelectric-to-antiferroelectric phase transition in NbOCl2 and a reversible ferroelectric-to-paraelectric phase transition in NbOI2 under a certain region of external pressure, accompanied by the greatly tunable nonlinear optical responses but with different microscopic mechanisms. Our study establishes the interesting external-field tunability of NbOX2 for nonlinear optical device applications.

Enriching the electronic populations of D-π-A type ON-OFF solar switches with sp2 hybridization: A TD-DFT possibility to create pull-push effect

The ability of specific molecular acceptors in photovoltaic devices is determined by their structure and chemical composition. Multiscale computations are important to protect investigation design; hence, efforts and money could be saved. Using Density Functional Theory (DFT), the effect of sp2 hybridized nitrogen substitutions (Ns) at the specific positions of a solar cell dye, 2,2′-((4-heptyl-4,9,9-trihexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(methanylylidene)bis(3-oxo-2,3-dihydro-1H-indene-1-yl-2-ylidene)dimalononitrile (IDIC), is explored. The N-incorporated dyes (IDIC1-IDIC5) were optimized at their ground energy minima at the B3LYP level of DFT with 6-31G+(d,p) basis sets. From these optimized geometries, their UV–visible analysis was executed at the DFT functional of CAM-B3LYP/6-31G+(d,p) selected as a result of benchmarking their λmax values with experimental values of IDIC. The computed value was found to be 528 nm which was very near to its experimental value (540 nm). Interestingly, for all the new dyes, λmax had blue-shifted values of (502–513 nm) for IDIC1, IDIC2 and IDIC5 and red-shifted values (557–779 nm) for IDIC3 and IDIC4 as compared to IDIC. The highest second-order Non-Linear Optical (NLO) response of 1054 e.s.u was noted for IDIC4 and IDIC5 which had the lowest energy gaps. It was found that incorporating Ns has significantly decreased the energy gap of electron rearrangement.

Electronic, nonlinear optical, UV–vis and NBO analysis of methyl methacrylate for optoelectronic and optical applications: DFT study and impact of conformation

Using Density Functional Theory (DFT) and time-dependent DFT (TD-DFT), we studied a compound widely used in daily life, namely: Methyl Methacrylate (MMA) monomer in its two stable isomers, cis-MMA and trans-MMA. The impact of conformation on the optical and electronic properties of MMA was highlighted. Structural parameters and thermodynamic properties were also assessed, and allowed to discuss the stability and reactivity of this compound. In addition, analysis of optoelectronic and electronic properties, global reactivity descriptors, natural bond orbital (NBO), and hole and electron reorganization energies was performed. The absorption and fluorescence properties, as well as the linear and nonlinear optical (NLO) properties of MMA were also investigated. The findings show that MMA is an insulator due to its wide band gap of 6.20 eV. It also exhibits good optoelectronic properties with high average electric field values of about 5.90 × 109 Vm−1 for cis-MMA and 5.42 × 109 Vm−1 for trans-MMA and high electric displacement values of at least 14.65 × 10-2 cm−2 for cis-MMA and 14.33 × 10-2 cm−2 for trans-MMA, suggesting a potential use for the design of piezoelectric and pyroelectric materials. In addition, trans-MMA has a dielectric constant close to that of good insulators; while cis-MMA exhibits a dielectric behaviour close to that of polymeric substances. Further, these materials are thermodynamically stable in its two conformations, with a good reactivity which can lead to good ability of polymerization. The analysis of the UV–vis spectra revealed that both forms of MMA absorb and emit mainly in the UV and that the Stokes shift of MMA is low, reducing its potential use in devices such as solar cells. At NLO level, MMA isomers exhibit weak optical properties such as second- and third-order optical susceptibility and cannot suitable for second and third harmonic generation; however, the conformation enhances second-order NLO response by at least 2 times when moving from cis- to trans-MMA, whereas the third-order response is almost unaffected. In addition, the conformation also affects the electronic and optoelectronic properties of MMA.

Density Functional Theory Study of the Secondorder Nonlinear Optical Properties of Novel Fluorenone Derivatives

Based on the molecular structure of novel fluorenone derivative named FO52, a series of new molecules have been designed by extending its π-conjugated bridge and introducing electron donor or acceptor substituents. The electronic transition and second-order non-linear optical response properties of these fluorenone derivatives were theoretically studied in detail by using the density functional theory computational methods. The results showed that the non-linear optical response of the molecule FO52 can be improved by introducing five-membered heterocycles into its skeleton structure. In addition, the introduction of strong substituents results in significant enhancement of the first hyperpolarizability of molecular nonlinear optical properties. These fluorenone derivatives could be treated as excellent candidates for nonlinear optical materials due to the narrow energy gap of its frontier molecular orbitals, distinct intramolecular charge transfer character and large first hyperpolarizabilities

Theoretical Perspective on Two-State "ON-OFF" NLO Switch of Rh(III)-Azobenzene Complex with Considerable First Hyperpolarizability.

In this paper, a light-induced Rh(III)-azobenzene (azo) complex in its two conformations (cis- and trans-form) is analyzed via density functional theory methods, focusing on the geometrical and electronic structure, linear and second-order nonlinear optical (NLO) properties, as well as UV-vis absorption spectra. The results show that trans-Rh exhibits more obvious charge separation and more extensive π-conjugation than cis-Rh. The energy gaps (Egap) between the highest occupied molecular orbital and lowest unoccupied molecular orbital of cis-Rh and trans-Rh are as small as 0.28 and 0.36 eV, respectively. The unusual small Egap facilitates electronic transition and accompanies large NLO responses. In particular, cis-Rh and trans-Rh possess considerably large second-order NLO responses with the first hyperpolarizability (βtot) up to 7.0 × 104 a.u. ("OFF" state) and 8.5 × 104 a.u. ("ON" state), respectively. trans-Rh shows good π-conjugation and obvious electric delocalization relative to cis-Rh and thus a considerable βtot value. The switchable ratio of βtot (trans-Rh)/βtot (cis-Rh) is equal to 1.2, showing switch characteristics. UV-vis analyses indicate that the ON and OFF states can finely tune the absorption range due to the strongest absorption peaks of cis-Rh (301 nm) and trans-Rh (446 nm) lying in the UV and vis region, respectively. It is expected that the studied Rh(III)-azo complexes may be applied in the field of optoelectronics.

Host-Guest Symmetry Matching in Two Crystalline Magnesium Sulfate Oxalates Obtained Via a Solvent-Free Route.

The combination of π-conjugated oxalate anion with sulfate group has been explored in the solvent-free synthesis of two new magnesium sulfate oxalates. One of them has a layered structure crystallized in the noncentrosymmetric space group Ia, while the other has a chainlike structure crystallized in the centrosymmetric space group P21/c. The noncentrosymmetric solid has a wide optical bandgap and exhibits a moderate second-harmonic-generation response. Density functional theory calculations were carried out to disclose the origin of its second-order nonlinear-optical response.