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Density functional theory has been employed to study indolo[3,2,1-jk]carbazole donor-based dyes, incorporating one and two units of 2,4-dimethoxybenzene auxiliary donors. Electrostatic potential analysis highlights the dye with one auxiliary donor (D2) as having the highest charge-donating capability. Structural analysis shows that auxiliary donors enhance planarity, reduce steric hindrance, and improve π-conjugation. Highest occupied molecular orbital (−6.025 to −5.660 eV) and lowest unoccupied molecular orbital (−2.927 to −2.844 eV) of all dyes support efficient electron injection into the semiconductor and dye regeneration process. Auxiliary donors enhance chemical reactivity parameters, improving the suitability of these dyes for dye-sensitized solar cells (DSSCs). Inclusion of extra donors reduces the excitonic binding energy, minimizing recombination losses, and increases polarization, enhancing the charge injection efficiency. Additional analyses explored properties such as charge separation, charge transfer length, transition density matrix and non-covalent interactions. All dyes exhibit strong absorption (410–440 nm) in the visible region, confirming their applicability to DSSCs, while emission spectra provide insights into their fluorescence lifetimes. D2 demonstrates improved performance in specific properties. However, D3, with two auxiliary donors, achieves the best overall balance across other computed parameters. Indeed, the inclusion of auxiliary donors induces significant changes and may be considered as a valuable strategy for designing efficient DSSCs. [ABSTRACT FROM AUTHOR] more...

Context: In this work, we have studied different properties of a series of fullerenes, from C24 to C50 by confining hydrogen molecule inside their cavity. The compression of the hydrogen molecule upon encapsulation is evidenced by its altered bond length, while a slight expansion of the fullerene cages due to H2 confinement is also noted. The chemical reactivity parameters of both the empty and H2 confined fullerenes are computed, alongside an examination of the energy components through energy decomposition analysis. Analysis of the absorption spectra indicated that both H2 encapsulated and empty fullerenes exhibited absorption in the UV region. Nevertheless, the inclusion of H2 within the fullerene cages appeared to have minimal influence on the reactivity parameters and absorption spectra, as evidenced by the comparison between the sets of empty and H2-confined fullerenes. Methods: The computational work including the geometry optimization, followed by the frequency analysis and other parameters has been achieved using Gaussian09 software. For doing these calculations, B3LYP and CAM-B3LYP functionals along with 6–311 + G(d,p) basis set is used. In addition, MULTIWFN software has been considered for studying bonding analysis and energy decomposition analysis for the systems. [ABSTRACT FROM AUTHOR] more...

The development of efficient nonlinear optical materials is a leading-edge area of research, driven by the necessity of materials beneficial in optoelectronics and electronic applications. To address this, we explore the potential of superhalogen adsorbed oxisulflower as efficient non-linear optical (NLO) materials using computational design strategy within the framework of density functional theory (DFT). Specifically, we investigate the adsorption of BF4 superhalogen on oxisulflower and identify ten isomers with promising NLO properties. The stability of all the adsorbed systems is predicted through binding energy. BF4 adsorbed oxisulflower has been seen to bring substantial changes in dipole moment, polarizability and first order hyperpolarizability of oxisulflower derivative. Overall, the theoretical investigation of non-linear optical properties on superhalogen adsorbed oxisulflower may be useful for future non-linear optical materials. [ABSTRACT FROM AUTHOR] more...

Here, we studied the adsorption of hydrogen sulfide (H₂S) on H-decorated T-graphene and its potential application as a gas sensor using density functional theory (DFT) calculations. To explore the mechanism behind the superior gas detection ability of H-decorated T-graphene, we examined the adsorption and diffusion of H₂S on this two-dimensional (2D) material. Our findings indicate that hydrogen sulfide physisorbs on H-decorated T-graphene with a small binding energy, minimal charge transfer from the substrate to the molecule, and a binding distance of 2.22 Å. The main contribution to the adsorption energy arises from van der Waals London dispersion interactions. We observed a reduction in the energy bandgap of the system upon adsorption of the hydrogen sulfide molecule, which leads to an increase in electrical conductivity. Bader charge analysis shows a minor electronic charge transfer from the substrate to the molecule. A low diffusion energy barrier of 0.162 eV suggests that H₂S molecules can diffuse rapidly. The negative adsorption energy, along with a short recovery time and low diffusion barrier, supports the potential for designing a gas sensor to detect hydrogen sulfide. [ABSTRACT FROM AUTHOR] more...

Pentagraphyne (PG-yne), a recently predicted two-dimensional (2D) carbon allotrope with appealing properties, has opened up possibilities for a wide range of applications. In this study, we investigate the structural, electronic, optical, and electrical transport properties of a novel one-dimensional (1D) system called pentagraphyne nanotubes (PG-yneNTs), formed by rolling a PG-yne sheet, using density functional theory (DFT) calculations. We design PG-yneNTs with diameters ranging from 6.94 Å to 13.62 Å and employ state-of-the-art theoretical calculations to confirm their energetic, dynamic, and thermodynamic stability. Our electronic band structure calculations reveal that all these nanotubes are wide indirect band gap semiconductors. Remarkably, PG-yneNTs exhibit superior optical properties, including high absorption coefficients and absorption spectra covering the visible regime of the electromagnetic spectrum, making them potential candidates for visible-light-driven photocatalysis and solar cells. Interestingly, both the electronic and optical band gaps increase with the diameter of the nanotubes. Additionally, the observation of negative differential resistance (NDR) phenomena in (4, 0) PG-yneNT suggests their potential applications in NDR devices such as fast switches, frequency multipliers, and memory devices. [ABSTRACT FROM AUTHOR] more...

ABSTARCT: A new mesomorphic compartmental [N2O2] donor Schiff base ligand [H2L] has been synthesized and one corresponding polymeric cadmium(II) complex of the type [Cd-L]n {H2L = 4,6-bis((E)-1-(octadecylimino)ethyl) benzene-1,3-diol} is prepared by direct reaction of metal ion with ligand. Both the ligand and its Cd-complex do exhibit mesomorphic properties. The IR spectrum of the ligand clearly reveals that the ligand acts as a bi-negative tetradentate donor through the two sets of phenolate oxygen and azomethine nitrogen. Mesomorphic behavior of these compounds are investigated with the help of polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The organization of the ligand and complex molecules in the mesophase are investigated by X-ray diffraction techniques. The Schiff base ligand and its Cd-complex shows plastic columnar mesophase (Colp) at ∼82 and ∼86 °C, respectively. The polymeric Cd-complex is blue light emitter with a broad emission maximum at ∼475 nm on excitation at 380 nm. [ABSTRACT FROM AUTHOR] more...

Using density functional theory, we have investigated the usage of twin graphene as an anode material for potassium‐ion batteries (KIBs). Twin graphene demonstrates excellent structural and cycling stability, with minimal changes in lattice parameters and negative cohesive energy during K charge/discharge cycles. Notably, the host material (twin graphene) offers multiple stable adsorption sites for potassium ions. We even observed that the pristine twin graphene, which is a semiconductor, consequently becomes metallic upon potassium adsorption. Twin graphene provides a high theoretical capacity of 495.84 mAh/g, along with low diffusion barrier of 0.290 V for K diffusion. Furthermore, the high electrical conductivity and low open‐circuit voltage of the chosen host will definitely enhance its performance as a KIB material. The structural integrity of twin graphene is also retained with the adsorption of potassium ion, as checked through ab initio molecular dynamics simulation. These findings suggest that twin graphene may be considered as a promising anode material for KIBs. [ABSTRACT FROM AUTHOR] more...

Two-dimensional van der Waals heterostructures (vdW-HSs) have emerged as a promising method for designing high-performance nanoscale optoelectronic devices such as solar cells. Herein, we propose the vdW-HS BAs/MoSi2P4 within the context of density functional theory (DFT). The results demonstrate that the BAs/MoSi2P4 heterostructure showcases a direct band gap and exhibits a notable type II band alignment feature that enables the efficient charge separation of photoinduced electron–hole pairs. The optical absorption intensity of the individual monolayers (BAs and MoSi2P4) is significantly enhanced upon the formation of a vdW-HS. The carrier mobility of the vdW-HS is significantly high compared to that of the MoSi2P4 monolayer. The findings of our study demonstrate the potential of BAs/MoSi2P4 vdW-HS as a desirable candidate for next-generation optoelectronic devices. [ABSTRACT FROM AUTHOR] more...

Consequences of incorporation of magnesium atom(s) on structural and optoelectronic properties of wurtzite cadmium sulphide have been investigated from first-principle calculations. Like direct (Γ–Γ) band-gap end binary wurtzite cadmium and magnesium sulphide semiconductors, such incorporation also results in stable direct (Γ–Γ) band-gap wurtzite MgxCd1−xS semiconductor ternary alloys with band-gaps residing in the UV spectral region. Lattice constants (a0, c0) of specimens within the w-MgxCd1−xS system nonlinearly reduce, while fundamental band-gap (Eg) enhances with increasing Mg content. Optical characteristics of optically anisotropic wurtzite crystals are studied mainly with ordinary and extraordinary components of real and imaginary parts of the complex dielectric function and some other dependent optical parameters. Electronic transitions from valence S-3p to Mg-4s, Mg-4p, Cd-5s and Cd-4p states of conduction band jointly result in optical features of the ternary alloys. Each uniaxial wurtzite crystal shows birefringence. Optical energy gap (Eopt) of each ternary alloy, higher than the corresponding Eg, lies in the UV region. Calculated components of static optical constants for ternary alloys become lower, but critical point energies become higher for larger band-gap specimen and vice versa. High optical absorption of direct band-gap ternary alloys in the UV region leads them as a compatible semiconductor for fabricating faster UV optoelectronic devices with high efficiency. [ABSTRACT FROM AUTHOR] more...

In this study, thirteen donors with the same spacer and acceptor have been tested to model dyes for dye-sensitized solar cell. Amongst the thirteen donors, 7,7,13,13-tetramethyl-8,9,12,13-tetrahydro-2H,5H,7H,11Hpyrano[2′,3′:4,5]pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-2,5-dione is found to possess the highest oscillator strength amongst the other dyes in first excited state. This donor has been studied further with five different acceptors to make ten dyes (by also considering their conformers formed by twisting the dye by 180 ∘ about the bond joining the donor with the spacer) to make dyes of type-I, among which the dye with rhodanine acetic acid acceptor and its conformer have the lowest HOMO–LUMO energy gap E g , highest absorption wavelength in the absorption spectrum with high oscillator strength and low exciton binding energy in the first excited state as compared to the other eight dyes considered here. The rhodanine acetic acid-based dyes have shown to outperform all the other four acceptor-based dyes in terms of chemical reactivity parameters. All the ten dyes when tested further with the inclusion of an extra benzene spacer show enhanced overall performance, with the rhodanine acetic acid-based dyes showing the most planarity, highest absorption wavelength, more suitable reactivity parameters, etc. Correlation studies between the solar cell parameters and chemical reactivity parameters have also been conducted where a direct relationship between the chemical hardness of the dye and open circuit voltage has been observed. [ABSTRACT FROM AUTHOR] more...

Three push‐pull dyes with triphenylamine as donor, thiophene as spacer and fullerene‐based acceptors have been designed using density functional theory (DFT) for dye‐sensitized solar cells (DSSCs). Here, we have done a systematic case study by varying the acceptor of dye. PCBM type of acceptors are chosen. However, the main focus lies on the fact that fullerene C60, which is used as conventional fullerene in PCBM, is replaced by C30. Further, two more structures are derived, where C30 is changed by two of its doped counterparts, C10B10N10 and C10B10P10. Structural integrity of these dyes is checked and found to be stable. Their electronic properties also provide a good insight into their characteristics. Highest occupied molecular orbital (HOMO) energy level of the dyes is positioned under the redox potential of redox couple, I3−/I−, which means that the dyes can be regenerated. LUMO energy value of dyes with C30 and C10B10N10 lies above the conduction band of semiconductor, TiO2, and hence electrons from the excited state of the dyes can be injected into the conduction band edge of TiO2. For C10B10P10, lowest unoccupied molecular orbital (LUMO) lies slightly below the conduction band of TiO2 (for B3LYP functional). Therefore, few more configurations of C10B10P10 have been checked by replacing B and P atoms with C atoms. Notably, incorporation of solvent rules out this exception and all the dyes become eligible for electron regeneration also. Time‐dependent DFT (TDDFT) studies throw light on their photochemical properties, which is one of the interim criteria for any system getting selected as a dye in the DSSCs. [ABSTRACT FROM AUTHOR] more...

Using the density functional theory method, hydrogen storage capacity for Yttrium doped fullerene has been studied. Bonding of Y atom with that of C30 is due to the charge transfer taking place from the d-orbital of the Y atom to the 2p-orbital of the C atom of C30. It has been predicted that a single Y atom can adsorb 7 hydrogen molecules, whose binding energy falls within the range as suggested by the U.S. Department of Energy (DOE). Interaction of hydrogen on the metal is because of the Kubas interaction where charge donation occurs from the metal d-orbital to the hydrogen 1s-orbital and there is also back donation as a result the hydrogen adsorption energy is more than physisorption. However, H atoms in the H2 molecule is not getting dissociated, only a small elongation of H–H bond in the H2 molecule is observed. The gravimetric weight percentage for 5 Y atoms loaded fullerene C30, with each Y atom adsorbing 7 H2 molecules is recorded to be 8.060%, higher than the limit of 6.5% by DOE. These findings suggest Y doped fullerene C30 may be considered as a potential candidate for hydrogen storage devices. [ABSTRACT FROM AUTHOR] more...

A new photoluminescent disc-like copper (II) metallomesogen of the type [CuL2] {H2L = 2,4-bis((E)-((4-(hexadecyloxy)phenyl)imino)methyl)phenol} have been synthesized. The compounds were characterized by elemental analyses, Fourier transform infrared spectroscopy (FTIR), 1H, 13C nuclear magnetic resonance (NMR), ultraviolet – visible spectroscopy (UV – Vis), thermogravimetric analysis (TGA) and high-resolution mass spectrometry. Mesomorphic behavior of the compounds was probed with the help of polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The organization of the molecules in the mesophase was investigated by X-ray diffraction techniques. The ligand is non-mesogenic but the copper complex exhibited thermally stable columnar mesophases at about 86°C. The copper complex is a blue-light emitter both in solution and in the solid state. The Density Functional Theory (DFT) study was carried out using 6–31 G (d, p) basis set with unrestricted B3LYP level to obtain a stable, optimized structure, which revealed a distorted square-planar geometry for the copper complexes. [ABSTRACT FROM AUTHOR] more...

A novel statistical ink drop displacement (IDD) printer model for the direct binary search (DBS) halftoning algorithm is proposed. It is intended primarily for pagewide inkjet printers that exhibit dot displacement errors. The tabular approach in the literature predicts the gray value of a printed pixel based on the halftone pattern in some neighborhood of that pixel. However, memory retrieval time and the complexity of memory requirements hamper its feasibility in printers that have a very large number of nozzles and produce ink drops that affect a large neighborhood. To avoid this problem, our IDD model embodies dot displacements by moving each perceived ink drop in the image from its nominal location to its actual location, rather than manipulating the average gray values. This enables DBS to directly compute the appearance of the final printout without retrieving values from a table. In so doing, the memory issue is eliminated and the computation efficiency is enhanced. The deterministic cost function of DBS is replaced by the expectation over the ensemble of the displacements for the proposed model such that the statistical behavior of the ink drops is accounted for. Experimental results show significant improvement in the quality of the printed image over the original DBS. Besides, the image quality obtained by the proposed approach appears to be slightly better than that obtained by the tabular approach. [ABSTRACT FROM AUTHOR] more...

In this study, a magnesium ion rechargeable battery with twin‐graphene based anode material has been proposed and studied for its feasibility as a suitable option to replace the commercially available lithium‐ion rechargeable batteries. The adsorption of magnesium ion is tested at different sites on the substrate and adsorption at the trigonal sites is seen to be the most stable one. A 2×2×1 supercell of twin‐graphene is seen to accommodate a maximum of 8 Mg ions which gives a high theoretical capacitance of 496.2mAh/g. The Mg adsorbed anode material is seen to be thermodynamically stable in both single and fully accommodated systems. Nudged elastic band (NEB) calculations for the movement of Mg ions via different paths reveal a low diffusion barrier for the movement of ions which is indicative of higher diffusivity in the system and faster charging rates which render twin‐graphene as a suitable material for use in Mg‐ion batteries (MIB). [ABSTRACT FROM AUTHOR] more...

First-principle calculations are carried out to explore magnesium composition-dependent structural and optoelectronic features of wurtzite MgxZn1−xSe ternary alloys. Analyses show a nearly linear enhancement in lattice constants (a0, c0) but a reasonably nonlinear reduction in bulk modulus (B0) with increasing Mg composition. Successive incorporation of Mg atom(s) in place of Zn in the w-ZnSe crystal results in three direct-band gap (Γ–Γ) semiconductor ternary alloys. The fundamental band gap shows fairly nonlinear enhancement with increasing Mg composition. Each of the considered wurtzite specimens is optically anisotropic. The computed components of the refractive index give uniaxial birefringence. Peaks in the dielectric function spectrum of all the specimens in the ultraviolet (UV) region are contributed exclusively or collectively by Se-4p to Mg-4s, 3p and Zn-5s, 4p electronic excitations. With the enhancement in the fundamental band gap, static optical constants ε1(0), n(0) and R(0) of the specimens reduce, while critical point energy in their ε2(ω), k(ω), σ(ω), α(ω) spectra enhances. [ABSTRACT FROM AUTHOR] more...

Recently, we have predicted a two-dimensional (2D) material named pentagraphyne (PG-yne); due to its intriguing properties, it is proposed for a wide range of applications. In this work, we have explored the potentiality of PG-yne as an anode material for Li/Na ion batteries using the density functional theory. Its differential adsorption energy suggests that maximal eight Li/Na ions can be accommodated over the PG-yne surface. We have obtained a high theoretical capacitance of 680 mAh g–1 for Li/Na ions adsorbed on PG-yne. The reported theoretical capacitance of PG-yne as an anode material in lithium-ion batteries (LIBs) is moderately higher than that of previously reported 2D anode materials, whereas PG-yne for NIB application has a significantly higher capacitance than that of several previously studied anode materials. Moreover, the low open-circuit voltage along with low diffusion barriers (≤0.50 eV) and much higher electronic conductivity after the adsorption of Li/Na ions again suggest its applicability as an anode material. Further, the molecular transition rate study also confirms the faster diffusivity of Li/Na ions over the PG-yne surface. The high storage capacity and faster diffusion of Li/Na ions adsorbed on PG-yne are mainly due to the lightweight and unique atomic structure of PG-yne. [ABSTRACT FROM AUTHOR] more...

In this work, a donor–acceptor substituted aromatic system ((E)-N-((E)-3-(4 (dimethylamino)phenyl) allylidene)-4-(trifluoromethyl) benzenamine (DPATB) has been synthesized and its detailed photophysics of intramolecular charge transfer process have been explored on the basis of steady state absorption, fluorescence and time resolved spectroscopy in combination with density functional theory calculations. Large solvent dependency fluorescence spectral shift and the calculated large excited state dipole moment clearly indicate an efficient charge transfer occurring from the donor group to the acceptor moiety in the excited state. Effect on addition of acid and pH on steady state spectral properties further reveals excited state charge transfer character. Quantum chemical calculations were performed in order to study the conformation and polarity of DPATB at their ground as well as excited electronic states. The HOMO and LUMO molecular orbital pictures are obtained at DFT level using B3LYP functional and 6–311 + g(d,p) basis set which clearly support excited state intramolecular charge transfer process. The molecular electrostatic potential maps for the optimized ground state, donor twisted and acceptor twisted geometry shed insight on the electrostatic potential and charge distribution in a system which gives information about the reacting site of the probe and nature of the reaction. In this work, detailed photophysics of excited state intramolecular charge transfer process in donor–acceptor system (DPATB) was evaluated using steady state and time-resolved fluorescence spectroscopy in combination with density functional theory calculations. Large solvent dependency fluorescence spectral shift and the calculated large excited state dipole moment clearly indicate an efficient charge transfer occurring in DPATB. Molecular orbital pictures as obtained from DFT based computational analysis reveals a significant change in the distribution of electron density upon transition from HOMO to LUMO which confirms an ICT process occurring from the donor group to the acceptor moiety in the excited state. [ABSTRACT FROM AUTHOR] more...

As a typical volatile organic compound (VOC), N,N-dimethylformamide (DMF) is a popular solvent and tracer for environmental air quality monitoring. Highly selective detection with low electrical noise, quick response/recovery times, and superior sensitivity at room temperature against VOCs, especially at the parts per billion (ppb) level, continues to be a significant challenge in gas-sensing applications. To address the issue, herein we demonstrate an MoSe2/multiwalled carbon nanotube composite based chemiresitor sensor for the detection of DMF. MoSe2 with a layered sheetlike structure supports MWCNTs to enhance the specific surface area, thereby increasing the sensitivity (down to 0.1 ppm for DMF) and selectivity and improving the response over a wider range of relative humidities (30-80%). The composite-based sensor shows good sensitivity (12.3% for 5 ppm of DMF), better selectivity, and faster response (65 s) and recovery (90 s) times in comparison to the MoSe2 sensor (192, 392 s), respectively, and a consistent response over 35 days. Density functional theory simulations were employed to understand the adsorption process and sensing mechanism. An analysis revealed a negative adsorption energy of -716 meV, implying that the adsorption process is spontaneous and exothermic. Further, charge transfer (0.013 e) using the Bader scheme confirms the process to be physisorption in nature. The results were further supported using an electrochemical impedance spectroscopy analysis. These results indicate the great potential of the composite for selective and stable sensing of DMF over a wider range of relative humidities. The present work suggests that a composite of MoSe2 with MWCNTs could be useful to design DMF sensors with improved sensitivity and selectivity under various environmental conditions. [ABSTRACT FROM AUTHOR] more...

First principles calculations have been used to verify the ability for sensing nitrobenzene by the host systems, pristine C24 and transition metal (TM) doped C24ubscript>, viz., C24+TM (TM = Sc, Cr and Mn). All the TM doped host systems are energetically stable which is confirmed from their negative values of binding energy. To get a clear view of the participation of the orbitals of different atoms of the host and how they are modified on the adsorption of nitrobenzene, density of states has been explored. Finally, charge transfer between the hosts and the guest is also calculated. Nitrobenzene is adsorbed on both pristine and TM doped C24 fullerene, but with reasonable adsorption energy and achievable recovery time, Sc doped C24 emerges as the best sensor device for sensing nitrobenzene among the TM doped fullerenes. [ABSTRACT FROM AUTHOR] more...

A 'twin-graphene' bilayer-based nanoscale capacitor and nanoscale dielectric capacitor are designed using a density functional theory approach including van der Waals dispersion correction. A strong effect on electronic properties is observed for different stacking modes. The AB stacking mode is the most stable one among the considered stacking modes with a band gap of 0.553 eV. Our predicted energy and charge-storage capacities are higher than those of other nanoscale capacitors designed using other two-dimensional carbon allotropes. We designed a nanoscale dielectric capacitor by placing a 'twin-graphene like BN sheet' (n = 1–3) sandwiched between 'twin-graphene' layers. The capacitance decreases significantly in the nanoscale dielectric capacitor model compared to the nanoscale capacitor model. However, the measured capacitance is higher than that of the previously studied nanoscale dielectric capacitor models. The significant capacitance of our proposed models ensures their promising applications for designing next-generation nanoscale capacitors. [ABSTRACT FROM AUTHOR] more...

The article discusses the celebration of Professor Pratim Kumar Chattaraj's 65th birthday and his academic achievements. An international conference was organized in his honor, which brought together experts from various scientific disciplines to understand complex systems and processes. Professor Chattaraj's research work spans a wide range of topics, including ab initio calculations, density functional theory, chemical reactivity theory, and machine learning. To commemorate his birthday, a collection of papers from the conference is being published in the Theoretical Chemistry Accounts journal. The papers cover diverse topics such as chemical reactivity descriptors, aromaticity, energy components, electron density, and various applications in different research domains. The article expresses gratitude to Professor Chattaraj for his contributions to science and his support for young scientists. [Extracted from the article] more...

This article demonstrates the use of a p-MoS2/n-WO3 heterojunctions based ultra sensitive and selective chemiresistive ammonia sensor that operates at 200◦ C. Surprisingly, the composite based sensor exhibited significant enhancement in ammonia sensing as compared to MoS2 (p-type) and WO3 (n-type) counterparts. The device also displayed excellent response-recovery features over a wider range of ammonia concentration together with superior selective nature toward ammonia as compared acetone, ethanol, methanol, isopropanol, formaldehyde, benzene, and hydrogen sulfide. Empowered by better signal-to-noise ratio, ammonia detection down to 1 ppm has become possible and can be further improved with the use of serpentine type electrodes. The device has shown a relative response of 207% for 200 ppm of ammonia with response and recovery times of 80 and 70 s, respectively. Moreover, these experimental results were further supplemented by density functional theory (DFT) simulation that were used to understand the adsorption kinetics and the sensing mechanism. A significant amount of charge transfer (0.082 e) between the adsorbed ammonia molecule and the MoS2/WO3 surface has been predicted by Bader analysis. Analysis also revealed a large negative adsorption energy ≈3.86 eV (373 kJ/mol) per ammonia molecule, implying the adsorption process to be chemisorption in nature. The band structure analysis further confirmed that ammonia adsorption on MoS2/WO3 is accompanied by an increase in band gap (by ≈ 96 meV). The present work illustrates the potential use of composite based heterostructures for monitoring ammonia gas in real fields. [ABSTRACT FROM AUTHOR] more...

The structural and electronic properties of bilayer α2-graphyne under electric field are investigated using density functional theory. The results showed that monolayer and bilayer α2-graphyne are zero-gap semiconductors. The external electric field has a considerable effect on the energy band gap of bilayer α2-graphyne. The energy band gap of bilayer α2-graphyne increases with the increase in the applied electric field. The electric field perpendicular to the sheet opens the band gap up to 0.18 eV. Our finding opens up a possibility for designing graphyne based electronic devices which exhibit a controllable band gap. [ABSTRACT FROM AUTHOR] more...

Herein, we have proposed a novel two-dimensional (2D) carbon allotrope, namely pentagraphyne (PG-yne), which is energetically favourable than other graphyne members, including experimentally synthesized graphyne and graphdiyne monolayer. State-of-the-art theoretical calculations confirm that the new carbon allotrope is not only dynamically, thermally, and mechanically stable but also can withstand temperatures up to 1000 K. It shows intrinsic semiconducting nature and the band gap is tuned by the application of strain. It possesses a high electron mobility of 2.52 × 103 cm2 V−1 s−1 and exhibits extraordinary optical features covering the entire visible region and a part of the UV region as well. Remarkable carrier mobility along with its superior optical performance renders it to be a potential candidate for future electronics, photovoltaic solar cells, and optoelectronic devices. [ABSTRACT FROM AUTHOR] more...

We present a systematic study on structural, electronic, optical properties of C30 fullerene and its six doped counterparts, C10X10Y10 (where, X=B, Al and Y=N, P, As) based on density functional theory calculation. All the fullerenes are energetically stable with cohesive energy per atom ranging from −5 to −8 eV. Chemical reactivity parameters are significantly enhanced due to doping. Further, nonlinear optics reveal that dopants bring remarkable change in polarizability and first hyperpolarizability of C30 derivatives. This work ensures the important implementations of these systems in nonlinear optics as well as for designing optical protective materials. Finally, the electronic absorption spectra predict the possibility of using C30 and heterofullerenes as photocatalyst in the visible region and UV light protection material in the UV region. [ABSTRACT FROM AUTHOR] more...

The number of the potential energy calculations required by the quadratic string method (QSM), and the fast marching method (FMM) is significantly reduced by using Shepard interpolation, with a moving least squares to fit the higher-order derivatives of the potential. The derivatives of the potential are fitted up to fifth order. With an error estimate for the interpolated values, this moving least squares enhanced Shepard interpolation scheme drastically reduces the number of potential energy calculations in FMM, often by up 80%. Fitting up through the highest order tested here (fifth order) gave the best results for all grid spacings. For QSM, using enhanced Shepard interpolation gave slightly better results than using the usual second order approximate, damped Broyden-Fletcher-Goldfarb-Shanno updated Hessian to approximate the surface. To test these methods we examined two analytic potentials, the rotational dihedral potential of alanine dipeptide and the SN2 reaction of methyl chloride with fluoride. [ABSTRACT FROM AUTHOR] more...

We report a detailed experimental and theoretical investigation on the interaction between the bioactive benzthiazoline-2-thione (BTT) molecule and metal oxide surfaces suspended in aqueous solution. The metal oxides in their nanostructured form were synthesized via sol–gel synthesis. The interactions of BTT with α-Fe2O3 and NiO oxide surfaces were probed by using spectroscopic signatures with a suspension of nanoparticles in aqueous medium. The spectral change of BTT between its free state and bound state onto the suspended metal oxide surfaces in aqueous solution functions as the signature of significant interactions. BTT spectra exhibit a hypsochromic shift of about 4–7 nm when it is attached to both the α-Fe2O3 and NiO oxide surfaces. Density functional theory (DFT) calculations reveal that charge transfer takes place from BTT through the p-orbital of the exocyclic sulphur atom to the O-p dominated conduction band of α-Fe2O3 (O-terminated) and to the Ni-3d dominated valence band of the NiO surfaces. This extension of charge from BTT to the metal oxide surfaces is attributed as the origin of the hypsochromic shift in the UV-Vis spectra of the BTT molecule. [ABSTRACT FROM AUTHOR] more...

The first-principle calculation with many-body effects explore the electronic and optical properties of newly designed 'graphyne with BP at hexagonal ring' (labeled as BP-yne). Our calculations show that BP-yne surface is a direct band gap semiconductor having band gap greater than pristine graphyne and this band gap value is sufficient to overcome the endothermic character of water-splitting reaction and further indicates its possible photocatalytic activities. The Raman and IR spectra analysis indicates quite different feature compare to its structural analogous 'graphyne with 3BN at ring' which may help to identify it during synthesis. Its optical absorption can be tuned from near-infrared to UV region depending on the polarization of electric field vector. The optical band gap, as well as the strong absorption peak, lies in the near-infrared region (NIR) and this promising trait can be exploited in biomedical arena. [ABSTRACT FROM AUTHOR] more...

The stabilities and reactivities of two transition metal (, Zn)-doped structures of C fullerene have been investigated by density functional theory approach. We have observed a noticeable structural change in pristine C due to the substitution of one of its carbon atom by Cu or Zn atom. From our findings, it is found that the energy gap of CCu and CZn increases with respect to pristine C, thus making the two doped fullerenes more stable than their pristine counterpart. The reactivity parameters such as chemical hardness, chemical potential and electrophilicity index for these structures are also studied. Interestingly, our calculations reveal that both the doped fullerenes obey the maximum hardness principle and minimum electrophilicity principle. Also, from the electronic absorption spectra analysis, it can be inferred that the maximum absorption peak of the two heteroatom-substituted fullerenes CCu and CZn are shifted towards the longer wavelength region as compared to the pure C fullerene, which clearly indicates that a red shift is introduced on account of doping. [ABSTRACT FROM AUTHOR] more...

New hockey-stick-shaped 2,5-diphenyl-1,3,4-thiadiazole-containing mesogens have been designed and synthesised. These molecules possess 4-n-alkoxy chain at the elongated arm whereas and 4-n-butyloxy chain at the shorter arm of the molecule. The compounds are fluorescent and emission located in the violet to blue region with a large stoke shift observed in polar solvents. No substantial solvatochromic effect was found in the absorption maxima, but in the emission, a red shift was observed with increasing the solvent polarity. In the solid thin film, compounds emitted green light. The compounds having longer chain (n> 8) exhibit SmA and SmC phase, while the compounds with shorter chain at one end of the molecule display nematic and SmC phase. The density functional theory study has been carried out to investigate the stable configuration and the influence of solvent on bond length, bond angle, bending angle, dipole moment, polarisability of the molecule. It also enables us to predict the possible reactive sites and effect of solvent on the chemical reactivity descriptors. Our study concludes that the molecule becomes more reactive in solvent compared to gas. The large voltage holding ratio confirms that this molecule may be used for active matrix display applications. [ABSTRACT FROM AUTHOR] more...

The present study emphasizes on structural, opto-electronic, vibrational, and nonlinear properties, at the electronic structure level, on the 4-fluoro-4-hydoxybenzophenone molecule using the first principles calculation. Detailed vibrational assignments of the wavenumbers are carried out on the basis of potential energy distribution and a good agreement between the reported and calculated wavenumbers has been observed. Furthermore, the molecular electrostatic potential surface predicts the reactive site of the molecule. From the time dependent density functional theory analysis of UV-visible spectra, a red shift has been observed at the maximum absorption wavelength when the gaseous medium is replaced by a solvent medium. The 4-fluoro-4-hydroxybenzophenone molecule possesses large hyperpolarizability value which implies its usefulness in nonlinear optical applications. [ABSTRACT FROM PUBLISHER] more...

A density functional theory based study is performed to investigate the noble gas (Ng = Ar-Rn) binding ability of nitrates, sulfates and carbonates of noble metal (M). Their ability to bind Ng atoms is assessed through bond dissociation energy and thermochemical parameters like dissociation enthalpy and dissociation free energy change corresponding to the dissociation of Ng bound compound producing Ng and the respective salt. The zero-point energy corrected dissociation energy values per Ng atom for the dissociation process producing Ng atom(s) and the corresponding salts range within 6.0-13.1 kcal/mol in NgCuNO, 3.1-9.8 kcal/mol in NgAgNO, 6.0-13.2 kcal/mol in NgCuSO, 3.2-10.1 kcal/mol in NgAgSO, 5.1-11.7 kcal/mol in NgCuSO, 2.5-8.6 kcal/mol in NgAgSO, 8.1-19.9 kcal/mol in NgAuSO, 5.7-12.4 kcal/mol in NgCuCO, 2.3-8.0 kcal/mol in NgAgCO and 7.3-18.2 kcal/mol in NgAuCO, with a gradual increase in moving from Ar to Rn. For a given type of system, the stability of Ng bound analogues follows the order as Au > Cu > Ag. All dissociation processes are endothermic in nature whereas they become endergonic as well in most of the cases of Kr-Rn bound analogues at 298 K. Natural population analysis along with the computation of Wiberg bond indices, and electron density analyses provide insights into the nature of the Ng-M bonds. The Ng-M bonds can be represented as partial covalent bonds as supported by the different electron density descriptors. [ABSTRACT FROM AUTHOR] more...

To ensure the possibility of using graphyne as a gas sensor, we have studied the adsorption of boron-halogenated system on pristine graphyne with the help of density functional theory using generalized gradient approximation. Depending on binding energy the most stable orientation, adsorption strength and optimal distance between the above mention molecules and graphyne surface have been determined. The band gap of graphyne slightly increases with the adsorption of the boron-halogenated system. The graphyne system behaves as n-type semiconductor when it interacts with BI and BCl molecules, and it behaves as p-type semiconductor when interaction with BF molecule takes place. Our result reveals that the electronic properties of pristine graphyne are highly influenced by the adsorption of boron-halogenated molecule. We have observed that pristine graphyne has zero electric dipole moment, but with the interaction of boron-halogenated molecule, a significant change in the electric dipole moment takes place. Hence, by measuring the electric dipole moment change, graphyne-based gas sensor can be design for the detection of above-mentioned molecules. [ABSTRACT FROM AUTHOR] more...

We propose a realization of mass varying neutrino dark energy in two extensions of the Standard Model (SM) with a dynamical neutrino mass related to the acceleron field while satisfying the naturalness. In the first scenario the SM is extended to include a TeV scale scalar Higgs triplet (ξ ) and a TeV scale second Higgs doublet (η), while in the second scenario an extension of the SM with fermion triplet (Σ) is considered. We also point out the possible leptogenesis mechanisms for simultaneously generating the observed baryon asymmetry of the universe in both scenarios and discuss the collider signatures for the TeV scale new fields which make these models testable in the current run of LHC. [ABSTRACT FROM AUTHOR] more...

Using spin-polarised density functional theory calculation single-walled carbon nanotube (SWCNT) whose sidewall is functionalised with nickel cluster is studied for its possible application in CO molecule sensing. We have chosen (6,0) SWCNT functionalised with Ni13cluster as the model for nanotube-cluster system. Changes in the properties of nanotube-cluster system brought by the CO molecule are reported. The CO molecule binding is energetically more favourable to the nanotube-cluster system than the pristine nanotube. The electronic properties are investigated in terms of density of states and bandstructure calculations. Pristine carbon nanotubes are intrinsically non-magnetic but nanotubes functionalised with nickel cluster are observed to have a huge magnetic moment which reduced on adsorbing CO molecule. The change in magnetisation upon CO adsorption may be detected using a suitable magnetometer. This result suggests the possibility of using carbon nanotube-cluster system to detect CO molecules. Bader charge analysis shows that CO molecule withdraws electronic charge from the cluster atoms. Nature of chemical bonding is studied with crystal orbital Hamilton population (–COHP) analysis. [ABSTRACT FROM AUTHOR] more...

This report aims to explore the possibility of using graphyne derivatives as UV-light protector. Boron (B) and nitrogen (N) atoms are systematically substituted into the structures, and we find that BN-substituted analogs exhibit distinct characteristics compared with their parent two-dimensional structure. Due to the presence of BN at different sites, the optical band gap is tuned from infrared to UV via visible region depending on substitution sites. These findings will lead the way to utilize these BN doped structures in various optoelectronic applications such as in hybrid solar cell, electroluminescence cell, light emitting cell, and as selective electromagnetic radiation absorber. The origin of this tunable optical response and band gap is explained in the light of partial density of states analysis and electron density distribution. The presence of strong absorption peak in UV region indicates that these materials may be used as an excellent candidate for UV light protection. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR] more...