Ground State Geometries Research Articles

The structure and rotationally resolved autodetachment spectrum of H15NO– and H14NO– near 3000 cm−1

The rotationally resolved vibrational autodetachment spectrum of the H15NO– anion has been observed in the region from 2932 to 3092 cm-1. rRKN branches were observed for K=4 through 8, and two rQKN branches with K=5 and 6 were assigned. The rQ5N branch of H14NO– has also been identified. The new observations have allowed a rotational analysis of H15NO– and have required a re-analysis of the previously observed spectrum of H14NO–. The spectra are consistent with a ground state (rm1) geometry of rNH=1.099Å, rNO=1.330Å, and ∠HNO=105.5°, in good agreement with the results of Ellis and Ellison for the NO bond length and comparing well with recent theoretical treatments of this anion. The band has been reassigned as the 0,2,0-(0,0,0) band.

Absorption and fluorescence spectroscopy of cold proflavine ions isolated in the gas phase.

Proflavine, a fluorescent cationic dye with strong absorption in the visible, has been proposed as a potential contributor to diffuse interstellar bands (DIBs). To investigate this hypothesis, it is essential to examine the spectra of cold and isolated ions for comparison. Here, we report absorption spectra of proflavine ions, trapped in a liquid-nitrogen-cooled ion trap filled with helium-buffer gas, as well as fluorescence spectra to provide further information on the intrinsic photophysics. We find absorption- and fluorescence-band maxima at 434.2 ± 0.1 and 434.7 ± 0.3nm, corresponding to a Stokes shift of maximum 48cm-1, which indicates minor differences between ground-state and excited-state geometries. Based on time-dependent density functional theory, we assign the emitting state to S2 as its geometry closely resembles that of S0, whereas the S1 geometry differs from that of S0. As a result, simulated spectra involving S1 exhibit long Franck-Condon progressions, absent in the experimental spectra. The latter displays well-resolved vibrational features, assigned to transitions involving in-plane vibrational modes where the vibrational quantum number changes by one. Dominant transitions are associated with vibrations localized on the NH2 moieties. Experiments repeated at room temperature yield broader spectra with maxima at 435.5 ± 1nm (absorption) and 438.0 ± 1nm (fluorescence). We again conclude that prevalent fluorescence arises from S2, i.e., anti-Kasha behavior, in agreement with previous work. Excited-state lifetimes are 5 ± 1ns, independent of temperature. Importantly, we exclude the possibility that a narrow DIB at 436.4nm originates from cold proflavine cations as the band is redshifted compared to our absorption spectra.

Introducing hafnium to atomically small- and medium-sized tin clusters (HfSnn0/-/2- (n = 4–17)): A computational investigation of geometrical and growth behavior, spectral properties, electronic configuration and thermochemistry

The global and local minimum configurations of single Hf atom doped Sn clusters are conducted via density function theory (DFT) combined with artificial bee colony algorithm (ABCluster). Furthermore, DFT method is also used to systematically investigate on their structural growth evolution, spectral and electronic information, thermochemical properties following the size of tin clusters doped Hf atom. Structurally, the ground-state geometries of neutral, anion and di-anion are discovered that, from n = 4, the number of Sn atoms in cluster, HfSnn0/-/2- adsorb additional Sn atom on the prior architecture one by one until forming n = 17 for HfSnn-10/-, as well as forming n = 16 for HfSnn-12-. And for the HfSn110/- and HfSn102- as beginning the species veritably develop sealed architectures. The strongest vibrational modes of sealed nanoclusters are stretching modes of Hf atom with infrared actives and breathing modes of the Sn cage framework with Raman actives, respectively. The natural population analysis (NPA) elucidates the stronger relationship between the Hf atoms and the tin frameworks in sealed clusters than that in unsealed clusters. The results of thermochemical properties, molecular orbital shell (MOs), adaptive natural density partitioning (AdNDP) and ultraviolet visible absorption spectrum (UV–Vis) indicate that, the HfSn16 with high symmetry of Td exhibits thermochemical stability and optoelectronic properties, which is utilized potentially as zero-dimensional unit of self-assembling fluorescent nanomaterials.

Palladium(II) Complexes of 4-Phenyl-3-thiosemicarbazone Ligands: Insights Into Cytotoxic Properties and Mode of Cell Death.

Reactions between sodium tetrachloropalladate and 2- (or 4-) substituted 4-phenyl-3-thiosemicarbazone ligands (HLR), with various electron-donating and electron-withdrawing substituents (R = OCH3, NO2, and Cl), afford square-planar complexes of the general formula [Pd(LR)2]. Ground-state geometry optimization and the vibrational analysis of cis- and trans-isomers of the complexes were carried out to get an insight into the stereochemistry of the complexes. Natural bond orbital analysis was used to analyze how the nature of the substituent affects the natural charge of the metal center, the type of hybridization, and the strength of the M-N and M-S bonds. Using spectrophotometry, the stability of the complexes, and their DNA binding abilities were assessed. The Pd(II) complexes showed moderate cytotoxicity against MCF-7 and Caco-2 cell lines, two of the assessed malignant cell lines, resulting in all known cell death types, including early apoptotic bodies and late apoptotic vacuoles as well as evident necrotic bodies.

Solvation effects on the excitation dynamics, structural and photorelaxation, quantum chemical investigation, and photophysical properties of 2D p-expanded quinoidal terthiophene (2DQTTs): Outlook from Ab-initio calculations

All dyes have different degrees of absorption. The present study delves into the intricate interplay between solvation and the photophysical behaviors of 2D p-expanded quinoidal terthiophene (2DQTT) dye compounds represented as A3, A4, and A5. In this study, a comprehensive investigation is presented, elucidating how solvation impacts excitation dynamics, ground and excited state geometry, photophysical characteristics. and photorelaxation dynamics of 2DQTTs. The energy gap data shows that the energies of the compounds increased in polar mediums and were greater for compound A3 which had ΔE values of 3.5227 eV in water, and 3.5225 eV in DMSO while compound A5 had the highest ΔE in all phases, with a ΔE value of 3.5453 eV in EtOH. Relaxation of the compounds leads to changes in the bonds and structural conformation of the 2D P-expanded quinoidal terthiophene (2DQTT) compounds as the compounds de-excite back to a lower energy level, and the photon causes a change in structural bonding (Stokes shift) in the heteroatoms which was taken into consideration. This manuscript not only advances our fundamental understanding of the interactions between solvation and molecular structure but also provides valuable insights into optimizing the performance of 2DQTT in optoelectronic devices as the compounds display a high absorption band in all phases, especially in water medial with compound A3, A4 and A5 recording absorbances of 785.32 nm, 787.13 nm, and 786.78 nm respectively, a high light harvesting efficiency LHE, great electron exciton energy and an injecting capacity (ΔGinject) greater than 0.20 eV in all phases. This work contributes significantly to the design and application of novel materials for next-generation optoelectronic technologies hence we hope that experimental research tests the studied compound towards the mentioned application.

Self-Trapped Excitons in Metal-Halide Perovskites Investigated by Time-Dependent Density Functional Theory.

We present a theoretical study of the formation of self-trapped excitons (STEs) and the associated broadband emission in metal-halide perovskites Cs4SnBr6 and Cs2AgInCl6, using time-dependent density functional theory (TDDFT) with the dielectric-dependent hybrid (DDH) functional. Our approach allows for an accurate description of the excitonic effect and geometry relaxation in the electronic excited states and yields optical gap, STE emission energy, and emission spectra in reasonable agreement with experiments. We point out the significance of considering geometry relaxations in the electronic excited state by showing that the exciton-phonon coupling computed in the ground-state atomic geometry is insufficient to describe the physical properties of STEs. Overall, we find that TDDFT with the DDH hybrid functional is a suitable approach for the study of the formation of STEs in perovskite and provides insights for designing metal-halide perovskites with tailored emission properties.

Single crystal of barium bis para-nitrophenolate para-nitrophenol tetrahydrate for NLO applications: crystal growth and DFT analysis

Abstract Single crystals of barium bis para-Nitrophenolate para-Nitrophenol tetrahydrate (BBPNT) were grown via the slow evaporation technique. The crystal dimensions were measured to be 15 mm × 10 mm × 6 mm. The BBPNT crystal was analyzed using X-ray diffraction, FTIR spectrum, UV–vis spectrum, dielectric studies, thermo-gravimetric (TG) differential thermal analyses (DTA), Vickers microhardness test, second-harmonic generation efficiency, Z-scan technique, PL spectra, and laser damage threshold studies. These findings were previously published in our paper. In the current situation, the theoretical methods include analyzing several aspects, such as the molecular structure determined using X-ray experimentation at its lowest energy state. This analysis is then contrasted by means of density functional theory (DFT) with a suitable set of basic functions. The first-order hyperpolarizability may also be determined via the use of Density Functional Theory (DFT) methods. The molecule’s stability, resulting from hyper conjugative interactions, was examined using the natural bond orbital approach to analyses its nonlinear optical activity and charge delocalization. The magnitude of the HOMO–LUMO energy gap indicates the potential for charge transfer inside the molecule. The investigation of donor-acceptor interactions was conducted using NBO analysis based on optimized ground state geometries.

Designing Thieno[3,4-c]pyrrole-4,6-dione Core-Based, A2-D-A1-D-A2-Type Acceptor Molecules for Promising Photovoltaic Parameters in Organic Photovoltaic Cells.

Nonfullerene-based organic solar cells can be utilized as favorable photovoltaic and optoelectronic devices due to their enhanced life span and efficiency. In this research, seven new molecules were designed to improve the working efficiency of organic solar cells by utilizing a terminal acceptor modification approach. The perceived A2-D-A1-D-A2 configuration-based molecules possess a lower band gap ranging from 1.95 to 2.21 eV compared to the pre-existing reference molecule (RW), which has a band gap of 2.23 eV. The modified molecules also exhibit higher λmax values ranging from 672 to 768 nm in the gaseous and 715-839 nm in solvent phases, respectively, as compared to the (RW) molecule, which has λmax values at 673 and 719 nm in gas and chloroform medium, respectively. The ground state geometries, molecular planarity parameter, and span of deviation from the plane were analyzed to study the planarity of all of the molecules. The natural transition orbitals, the density of state, molecular electrostatic potential, noncovalent interactions, frontier molecular orbitals, and transition density matrix analysis of all studied molecules were executed to validate the optoelectronic properties of these molecules. Improved charge mobilities and dipole moments were observed, as newly designed molecules possessed lower internal reorganization energies. The open circuit voltage (Voc) of W4, W5, W6, and W7 among newly designed molecules was improved as compared to the reference molecule. These results elaborate on the superiority of these novel-designed molecules over the pre-existing (RW) molecule as potential blocks for better organic solar cell applications.

Spectroscopic and Theoretical Investigation of High-Spin Square-Planar and Trigonal Fe(II) Complexes Supported by Fluorinated Alkoxides.

The electronic structures and spectroscopic behavior of three high-spin FeII complexes of fluorinated alkoxides were studied: square-planar {K(DME)2}2[Fe(pinF)2] (S) and quasi square-planar {K(C222)}2[Fe(pinF)2] (S') and trigonal-planar {K(18C6)}[Fe(OC4F9)3] (T) where pinF = perfluoropinacolate and OC4F9 = tris-perfluoro-t-butoxide. The zero-field splitting (ZFS) and hyperfine structure parameters of the S = 2 ground states were determined using field-dependent 57Fe Mössbauer and high-field and -frequency electron paramagnetic resonance (HFEPR) spectroscopies. The spin Hamiltonian parameters were analyzed with crystal field theory and corroborated by density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) calculations. Whereas the ZFS tensor of S has a small rhombicity, E/D = 0.082, and a positive D = 15.17 cm-1, T exhibits a negative D = -9.16 cm-1 and a large rhombicity, E/D = 0.246. Computational investigation of the structural factors suggests that the ground-state electronic configuration and geometry of T's Fe site are determined by the interaction of [Fe(OC4F9)3]- with {K(18C6)}+. In contrast, two distinct countercations of S/S' have a negligible influence on their [Fe(pinF)2]2- moieties. Instead, the distortions in S' are likely induced by the chelate ring conformation change from δλ, observed for S, to the δδ conformation, determined for S'.

Synthesis, Characteritation, Optoelectronic Properties and DFT Studies of Novel 4,5‐Diarylpyrazole‐1‐Carboxylates

AbstractIn the present work, a well organised pathway for the eco‐friendly synthesis of a series of 4,5‐diarylpyrazole‐1‐carboxylates has been reported. The resulted compounds were characterized by different spectroscopic techniques (IR, 1H‐NMR & 13C‐NMR and HRMS). To shed light on various properties of interests, density functional theory (DFT) was utilized to optimize the ground state geometry of synthesized pyrazoles. Time dependent density functional theory (TDDFT) was used to investigate the impact of various functionals on the absorption wavelength i.e., B3LYP, M062X, BHandHLYP, B3P86, CAM‐B3LYP, and PBE0. Among all these functional, CAM‐B3LYP and BHandHLYP were in good consent with the experimental results. With an aim to enhance the optoelectronic properties, 10 new derivatives were designed by varying the various substituents on the aryl ring. Among all these synthesized pyrazole molecule, Methyl 4‐(4‐Methoxyphenyl)‐5‐(3‐nitrophenyl)‐1H‐pyrazole‐1‐carboxylate 3a and Methyl 4‐(4‐Methoxyphenyl)‐5‐(4‐nitrophenyl)‐1H‐pyrazole‐1‐carboxylate 3b exhibited better optoelectronic properties with HOMO‐LUMO gap of 3.38 eV. To the best of our knowledge, the studies of photophysical properties of these 1,4,5‐trisubstituted pyrazoles for optoelectronic uses has been reported first time by our research group.

Molecular level interaction, HOMO-LUMO, MEP, UV–Vis, Hirshfeld, topological analysis, and in-vitro of isoflavones from Eremostachys Vicaryi Benth. Ex Hook. f.

Eremostachys vicaryi Benth. Ex Hook. f. (Labiatae), a Pakistani (Baluchistan) herbal medicinal plant commonly known as “Stagh,” which has a sharp taste and smell. It acts as an antiseptic and antimicrobial agent and is used for fish poisoning, treating skin diseases, and holding a cooling effect. Following the assessment of the plant extract's cytotoxic and phytotoxic assays using phytochemical screening, the antioxidant and anti-inflammatory properties of the pure ingredients that were separated from the ethyl acetate soluble fractions have been evaluated. The bioassay-guided fractionation and purification of E. vicaryi B. crude methanol extract yielded two isoflavones (1–2) that showed promising antioxidative activities with DPPH and cytochrome-c-reduction assays. Compounds 1 and 2 have shown considerable anti-inflammatory efficacy, 1 being a good inhibitor of the superoxide within the living system. Initial assumptions on the one-electron transfer process indicated that Compound 1 has a smaller ionization potential value compared to Compound 2 and so has greater antioxidant potential than its predecessor, isoflavone. Moreover, the anti-inflammatory and antioxidant activity of isoflavones was also probed by first-principles calculations. Based on the findings, it has been concluded that the crude extract of E. vicaryi B. and its organic components exhibit noteworthy phytotoxic and cytotoxic properties. The isolated pure isoflavones 1 and 2 showed significant antioxidant and anti-inflammatory activities. Solute-solvent interactions were studied and reported for both compounds. An analysis was conducted on the UV–Vis electronic transition for different solvents. Using a Multiwave function analyzer the topological findings such as ELF, LOL, and RDG were done to comprehend the surface electron density, delocalization, localized orbital, and weak interaction in the compounds. The antioxidant activity is evaluated by radical methods using DPPH, and cytochrome-c-reduction assays using ascorbic acid as a standard. Through cell-based respiratory burst testing, the anti-inflammatory activity of standard indomethacin was examined. The ground state geometries of isoflavones and reference compounds were optimized by Density Functional Theory- (DFT) by computing various electronic properties. In-vitro bioassay results were validated by first-principles calculations.

Cross-over from pyrene to acene optical and electronic properties: a theoretical investigation of a series of pyrene derivatives fused with N-, S, and O-containing heterocycles.

Pyrene and acene derivatives are an important source of materials for optoelectronic device applications both as emitters and organic semiconductors. The mobility of major charge carriers is correlated with the coupling constants of the respective major charge carrier as well as the relaxation energies. Herein, we have applied range-separated density functionals for the estimation of said values. A series of five alkylated derivatives of pyrene laterally extended by heteroaromatic or phenyl groups were explored and contrasted to nascent pyrene, alkylated pyrene and tetracene. The ground state geometries along with absorption properties and relaxation energies are presented as well as a discussion of the suitability of the material toward hole and electron transport materials.

Real-time observation of sub-100-fs charge and energy transfer processes in DNA dinucleotides.

Using as showcase the DNA dinucleotide 5'-dTpdG-3', in which the thymine (T) is located at the 5' end with respect to the guanine (G), we study the photoinduced electronic relaxation of coupled chromophores in solution with an unprecedented refinement. On the one hand, transient absorption spectra are recorded from 20 fs to 45 ps over the 330-650 nm range with a temporal resolution of 30 fs; on the other hand, quantum chemistry calculations determine the ground state geometry of the 4 possible conformers with stacked nucleobases, the associated Franck-Condon states, and map the relaxation pathways leading to excited state minima. Important spectral changes occurring before 100 fs are correlated with concomitant G+ → T- charge transfer and T → G energy transfer processes. The lifetime of the excited charge transfer state is only 5 ps and the absorption spectrum of a long-lived nπ*T state is detected. Our experimental results match the transient spectral properties computed for the anti-syn conformer of 5'-dTpdG-3', which is characterized by the lowest ground state energy and differs from that encountered in B-form duplexes.

Simulating transient X-ray photoelectron spectra of Fe(CO)5 and its photodissociation products with multireference algebraic diagrammatic construction theory.

Accurate simulations of transient X-ray photoelectron spectra (XPS) provide unique opportunities to bridge the gap between theory and experiment in understanding the photoactivated dynamics in molecules and materials. However, simulating X-ray photoelectron spectra along a photochemical reaction pathway is challenging as it requires accurate description of electronic structure incorporating core-hole screening, orbital relaxation, electron correlation, and spin-orbit coupling in excited states or at nonequilibrium ground-state geometries. In this work, we employ the recently developed multireference algebraic diagrammatic construction theory (MR-ADC) to investigate the core-ionized states and X-ray photoelectron spectra of Fe(CO)5 and its photodissociation products (Fe(CO)4, Fe(CO)3) following excitation with 266 nm light. The simulated transient Fe 3p and CO 3σ XPS spectra incorporating spin-orbit coupling and high-order electron correlation effects are shown to be in a good agreement with the experimental measurements by Leitner et al. [J. Chem. Phys., 2018, 149, 044307]. Our calculations suggest that core-hole screening, spin-orbit coupling, and ligand-field splitting effects are similarly important in reproducing the experimentally observed chemical shifts in transient Fe 3p XPS spectra of iron carbonyl complexes. Our results also demonstrate that the MR-ADC methods can be very useful in interpreting the transient XPS spectra of transition metal compounds.

Regioselective Synthesis of 2,4- and 2,5-Disubstituted 1,3-Thiazoles from 2-Oxo-2-(amino)ethanedithioates via Base-Catalyzed Cyclization

AbstractFacile and efficient methods are reported for the synthesis of 2,4- and 2,5-disubstituted-1,3-thiazoles by the cyclization of 2-oxo-2-(amino)ethanedithioates with TosMIC and α-haloketones in high yields. Key structures were confirmed based on X-ray crystallographic studies. In addition, investigation of ground state geometry, electronic and molecular structural properties, FMOs, global reactivity descriptors, MEP and NCI analyses were predicted to access the information related to the stability, reactivity, and strength of the interactions present in the molecules by quantum chemical calculations. Further, the potency of derivatives was tested against the SARS-Cov2 receptor (PDB ID: 7mc6) via molecular docking approach with binding scores of –6.0 to –8.4 kcal/mol.

A selective and sensitive probes of chalcone derivative as a fluorescent chemosensor for the detection of Cr3+ ion

A new chalcone based chemosensor like 6-cinnamoylthiochroman-4-one (AZAN), has been designed and synthesized from 6-chlorothiochroman-4-one and cinnamaldehyde via keto ethylenic linkage. Its amino derivatives were synthesized by using urea (AZANU), thiourea (AZANTU) and 2,6-diamino pyridine (AZANPy) respectively and its metal ion sensing properties were investigated. The sensors can selectively recognize and sense the metal cations by showing different fluorescent characteristics at different concentrations. The fluorescence intensity shows remarkable enhancement by Cr3+ over other common metal ions (Cd2+, Hg2+ and Pb2+). The proposed mechanism can be confirmed by UV–Vis and emission titration. The newly synthesized receptor can sense the metal ions even in nano molar level. The binding or association constant and detection limit of chemosensor to Cr3+ are 1.684 × 105 M−1 and 0.2245 × 10−9 M respectively. A computation using the density functional theory was done to gain detailed insights into the electronic structures of the ligand and its derivatives. B3LYP function and 6-31G(d,p) basis set were used to optimize the ground-state geometry of the chemical and its derivatives.

Synthesis and investigation of the structure, thermal, optical, and electrical properties of poly (indol-thiazolo-thiadiazole) derivatives at room temperature

This research work is intended for the novel synthesis and study of structural, thermal, optical, electrical, and dielectric properties of semiconductor poly (2-amino-5-(1H-indolyl)-5H-thiazolo[4,3-b]-1,3,4-thiadiazole) (PAITTD) and its N-substituted indole derivatives with a side chain containing chlorobenzoyl (PACBITTD) and bromobenzene sulphonyl (PABBSITTD). The characterization techniques such as H1NMR, FTIR, SEM, and TGA/DSC ensured the structural and thermal properties of the as-synthesized polymers. In addition, the molecular weight of the PAITTD, PACBITTID, and PABBSITTD was calculated via H1NMR technique. The optical band gap as obtained from the absorbance study was found to be in the range of 1.5 eV to 2.58 Ev. Moreover, the ground-state geometries and the absorption wavelengths for the studied compounds were investigated by DFT and TD-DFT, where the theoretical results show coincidence with these of the experimental where the calculated (λmax) values are approximately near to the experimental (λmax) values for the PAITTD, PACBITTID, and PABBSITTD. The impedance ac conductivity and dielectric properties of the PAITTD, PACBITTID, and PABBSITTD were performed in the frequency ranges from 20 Hz to 10 MHz at room temperature, where their values were 3.0 × 10−7, 8.7 × 10−7, and 2.6 × 10−6, respectively. The Nyquist plot confirmed the presence of both grain and grain boundary effects for conducting PAITTD, PACBITTID, and PABBSITTD, and Double relaxation behavior was also observed. The variation of ac conductivity with frequency obeys the modification of Jonscher’s universal power law (JUPL). Based on the optical and electrical properties, synthetic PAITTD, PACBITTID, and PABBSITTD are promising materials in the design of optoelectronic semiconductor devices.

A combined theoretical and experimental study of nickel derivative [Daiquiris(nicotinamide-jN1)nickel (II)]-lfumarato-K2O1:O4

The ground state geometry of the nickel derivative [Daiquiris(nicotinamide-jN1) nickel(II)]-fumarato-K2O1:O4 has been optimized and is being led toward its quantum chemical analysis in this paper. For more accuracy, we used the 6-311[Formula: see text]G (d, p) basis set for C, H, N, and O atoms and the LAN2DZ basis set for Ni. The calculated and experimental infrared (IR) spectra for the title molecule are well correlated, and the correlation factor [Formula: see text] shows that the method effectively interprets the molecule’s IR spectra. The electronic properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and associated energy gap have been calculated by Time-Dependent Density Functional Theory (TD-DFT) approach. The natural bond orbital (NBO) analysis of the molecule describes how interatomic charge transfer results in the formation of bonding–nonbonding interactions. The experimental and calculated Ultraviolet visible (UV-Vis) spectra are compared. We anticipate our work will inspire fresh approaches to the title molecule’s ongoing research.

H2O-HCN complex: A new potential energy surface and intermolecular rovibrational states from rigorous quantum calculations.

In this work the H2O-HCN complex is quantitatively characterized in two ways. First, we report a new rigid-monomer 5D intermolecular potential energy surface (PES) for this complex, calculated using the symmetry-adapted perturbation theory based on density functional theory method. The PES is based on 2833 abinitio points computed employing the aug-cc-pVQZ basis set, utilizing the autoPES code, which provides a site-site analytical fit with the long-range region given by perturbation theory. Next, we present the results of the quantum 5D calculations of the fully coupled intermolecular rovibrational states of the H2O-HCN complex for the total angular momentum J values of 0, 1, and 2, performed on the new PES. These calculations rely on the quantum bound-state methodology developed by us recently and applied to a variety of noncovalently bound binary molecular complexes. The vibrationally averaged ground-state geometry of H2O-HCN determined from the quantum 5D calculations agrees very well with that from the microwave spectroscopic measurements. In addition, the computed ground-state rotational transition frequencies, as well as the B and C rotational constants calculated for the ground state of the complex, are in excellent agreement with the experimental values. The assignment of the calculated intermolecular vibrational states of the H2O-HCN complex is surprisingly challenging. It turns out that only the excitations of the intermolecular stretch mode can be assigned with confidence. The coupling among the angular degrees of freedom (DOFs) of the complex is unusually strong, and as a result most of the excited intermolecular states are unassigned. On the other hand, the coupling of the radial, intermolecular stretch mode and the angular DOFs is weak, allowing straightforward assignment of the excitation of the former.

Understanding Photophysical Properties of Molecules Relevant in Organic Semiconductor Laser Diodes from Electron Localization Function-Tuned and Solvent-Tuned Range-Separated Functionals.

Organic semiconductor laser diodes (OSLDs) are prevalent in optoelectronics because of their sustainable energy applications. Organic molecules used in such diodes are usually large; hence, their studies are computationally challenging with high-end benchmark methods. Computational methods with reliable accuracy and efficiency are always indispensable. In the present work, we have applied our computationally inexpensive, nonempirically tuned [electron localization function (ELF*) and solvent (Sol*)] range-separated (RS) functionals to study five molecules used in OSLDs. The emission energies in three different environments [toluene, CBP (4,4'-bis(n-carbazolyl)-1,1'-biphenyl) film, and gas] have been computed with the tuned functionals and compared with the experimental emission energies. ELF* and Sol* functionals can accurately reproduce emission energies in toluene and CBP film environments. On the other hand, both ELF* and IP-tuned functionals with excited-state geometry (IP*) perform better in the gas phase. In addition, a comparative study is performed between time-dependent density functional theory and the Tamm-Dancoff approximation. Along with the emission energy, oscillator strength values have also been reported. Different IP-tuned RS parameters were obtained with the ground- and excited-state geometries. Interestingly, it has been observed that the optimally tuned RS parameter with excited-state geometry (IP*) performs better compared to that with ground-state geometries (IP). Fractional occupation calculations show that the tuned functionals exhibit less localization and delocalization error. The study envisages that ELF* and Sol* functionals can be used to design future candidates for OSLDs.