IR Intensities Research Articles

Structural and Vibrational Investigation of Benzil-(1,2-Diphenylethane-1,2-Dione): Experimental and Theoretical Studies

Single crystals of benzil commonly known as 1,2-diphenylethane-1,2-dione are grown by the slow evaporation method at room temperature. Gaussian 09 program is applied for theoretical calculations with B3LYP/6-311++G(d,p) basis set. The structure is optimized, and the energy, structural parameters, vibrational frequencies, IR, and Raman intensities are determined. Complete natural bonding orbital (NBO) analysis is carried out to analyze the intramolecular electronic interactions and their stabilization energies. From the second-order perturbation theory analysis of the benzil molecule, it is observed that there exists a hyperconjugative intramolecular stabilization energy between 17.45 and 22.76 KJmol-1. HOMO-LUMO analysis has been performed to identify the charges transferred within the molecule. The energy gap is calculated to be 2.919 eV and thus establishes the soft nature of the molecule. The molecular electrostatic potential (MEP) of the grown crystal was analyzed using the B3LYP method with 6-311++G(d,p) basis set. First-order hyperpolarizability calculations reveal the nonlinear optical microscopic behavior of the benzil molecule with nonzero values. The total value of the first-order hyperpolarizability (βtot) is of the order of41.5246×10−31 esu, which is found to be 11.135 times that of urea. Hence, benzil can be referred to as a good material for nonlinear optical applications.

Infrared Spectra of 1-Quinolinium (C9H7NH+) Cation and Quinolinyl Radicals (C9H7NH and 3-, 4-, 7-, and 8-HC9H7N) Isolated in Solid para-Hydrogen.

Large protonated polycyclic aromatic hydrocarbons (H+PAH) and the corresponding nitrogen heterocycles (H+PANH) have been proposed as possible carriers of unidentified infrared (UIR) emission bands from galactic objects. The nitrogen atom in H+PANH is expected to induce a blue shift of the band associated with the CC-stretching mode of H+PAH near 6.3 μm so that their emission bands might agree better with the UIR band near 6.2 μm. We report the IR spectrum of protonated quinoline (1-quinolinium cation, C9H7NH+) and its neutral species (1-quinolinyl radical, C9H7NH) measured upon electron bombardment during the deposition of a mixture of quinoline (C9H7N) and para-hydrogen (p-H2) at 3.2 K, indicating that the protonation and hydrogenation occur mainly at the N atom site. Additional experiments on the irradiation of C9H7N/Cl2/p-H2 matrices at 365 nm to generate Cl atoms, followed by irradiation with IR light to generate H atoms via Cl + H2 (v = 1), were performed to induce the reaction H + C9H7N. This method proved to be efficient for hydrogenation reactions in solid p-H2; we identified, in addition to C9H7NH observed in electron-bombardment experiments, four radicals with hydrogenation at the C-atom site─3-, 4-, 7-, and 8-HC9H7N. Spectral assignments were achieved according to the behavior upon secondary photolysis and a comparison of experimental results with vibrational wavenumbers and IR intensities predicted with the B3LYP/6-311++G(d,p) method. The observed lines at 1641.4, 1598.4, and 1562.0 cm-1 associated with the CC-stretching mode of C9H7NH+ are blue-shifted from those at 1618.7, 1580.8, 1556.7, and 1510.0 cm-1 of the corresponding protonated naphthalene (C10H9+).

Synthesis, vibrational spectroscopic investigation, molecular docking, antibacterial and antimicrobial studies of a new anthraquinone derivative compound

A new anthraquinone derivative, 1-(2,5-dimethylpiperazin-1-yl)anthracene-9,10-dione, was synthesized and characterized by Fourier Transform-Infrared, Raman and nuclear magnetic resonance analysis. The optimized molecular geometry was obtained using Density Functional Theory, B3LYP method with a 6-311++G(d,p) basis set. The fundamental vibrational wavenumbers, IR and Raman intensities were calculated for the optimized structure and simulated spectra were compared with the experimental vibrational spectra. The calculated highest occupied molecular orbital and lowest occupied molecular orbital energies indicated the presence of charge transfer within the molecule. The antibacterial activities of the new amino anthraquinone derivate against gram-positive and gram-negative bacteria were determined. Molecular docking simulations were performed with the new anthraquinone derivative and DNA to reveal its anticancer property. It was found that the anthraquinone derivate was bound to DNA with a high binding affinity (ΔG = −31.8 kJ/mol) and interacted with the DG10, DC11 and DG16 residues via the intermolecular hydrogen bonds. Moreover, to investigate the antiviral activity of the compound and to expose its action mechanism as an antiCOVID-19 agent, in silico molecular docking studies were performed on the Angiotensin-Converting Enzyme-2, and SARS-CoV-2 targets (holo and apo forms of main proteases Mpro and spike glycoprotein).

Experimental Raman, FTIR and UV-vis spectra, DFT studies of molecular structures and barrier heights, thermodynamic functions and bioactivity of kaempferol

Molecular structures and vibrational parameters for the all the four possible conformers of kaempferol were investigated using Gaussian 09 and GAR2PED software. Raman and FTIR spectra of kaempferol were recorded in the regions 50–4000 cm−1 and 400–4000 cm−1, respectively and interpreted in the light of the computed quantities. Some of the modes were found to have conformer dependent frequencies, IR and Raman intensities and depolarisation ratios. The complex, broad and intense IR band in the range 2900–3500 cm−1 is explained to arise due to the four OH stretching and an overtone modes. The barrier heights for the OH tops against internal rotations have been determined. The UV–vis absorption spectrum was measured in the range 220–800 nm. MEP and HOMO-LUMO energies were computed for all the four conformers and NBO analysis was carried out. Thermodynamic functions of title compound have been carried out. Different bioactivity scores for this molecule were computed.

Nitrile IR intensities directly measure electric fields in protic and non-protic environments

Nitriles are useful vibrational probes; the interpretation of their frequencies, however, is complicated by hydrogen bonding in protic environments. Here we observed a vibrational Stark effect (VSE) which correlates electric field to transition dipole moment (and, by extension, the nitrile peak area) instead of to frequency. This VSE governs the transition dipole moment for the CO stretch in acetophenone and the CN stretch in benzonitrile, with studies performed in bulk-phase solvents. While modest for the acetophenone carbonyl CO, the VSE for the benzonitrile nitrile CN is dramatic, and a >300% increase in absolute peak area from hexanes to water.

Vibrational Spectroscopic and Molecular Docking Studies of Amrinone, a Cardiotonic Inotropic Drug-=SUP=-*-=/SUP=-

Amrinone is a class I cardiotonic inotropic agent, which is known to increase the cyclic adenosine monophosphate (cAMP) level by inhibiting the phosphodiesterase 3 (PDE3) enzyme. In this study the theoretically possible stable conformations of the amrinone, was examined first by conformational analysis method and then the obtained most stable conformation was optimized by DFT/wb97xd/6-311++G(d,p) level of theory using Gaussian 03 program. The credibility of the theoretical model was confirmed by comparison of experimental and theoretical vibrational spectra of the title molecule. The fundamental vibrational wavenumbers, IR and Raman intensities of the optimized structure of amrinone were determined using DFT/wb97xd/6-311++G(d,p) level of theory and compared with the experimental vibrational spectra. To investigate the influence of amrinone on cAMP enhancement, the docking simulations towards PDE3B were carried out and the main binding interactions of amrinone with PDE3 were elucidated. Cytochrome P450s (CYPs) are very important phase I metabolizing enzymes. The interaction between amrinone and CYPs (CYP1A2, CYP2C9 and CYP2C19) was investigated by docking simulations. Moreover, molecular docking of the title molecule with different proteins and receptors were studied to reveal potential mechanisms for therapeutic applications. Molecular docking simulations revealed that amrinone showed strong binding affinity to integrins α5β1 (Delta G=-6.6 kcal/mol) and αIIbβ3 (-6.6 kcal/mol), and DNA (-6.5 kcal/mol). The results correlated with its anticancer activity. The drug likeness and ADMET properties of amrinone were analyzed for the prediction of pharmacokinetic profiles. Key words: amrinone, DFT calculations, FTIR, Molecular Docking, ADMET.

Vibrational Spectroscopic and Molecular Docking Studies of Amrinone, a Cardiotonic Inotropic Drug

Amrinone is a class I cardiotonic inotropic agent, which is known to increase the cyclic adenosine monophosphate (cAMP) level by inhibiting the phosphodiesterase 3 (PDE3) enzyme. In this study the theoretically possible stable conformations of the amrinone, was examined first by conformational analysis method and then the obtained most stable conformation was optimized by DFT/wb97xd/6-311++G(d,p) level of theory using Gaussian 03 program. The credibility of the theoretical model was confirmed by comparison of experimental and theoretical vibrational spectra of the title molecule. The fundamental vibrational wavenumbers, IR and Raman intensities of the optimized structure of amrinone were determined using DFT/wb97xd/6-311++G(d,p) level of theory and compared with the experimental vibrational spectra. To investigate the influence of amrinone on cAMP enhancement, the docking simulations towards PDE3B were carried out and the main binding interactions of amrinone with PDE3 were elucidated. Cytochrome P450s (CYPs) are very important phase I metabolizing enzymes.The interaction between amrinone and CYPs (CYP1A2, CYP2C9 and CYP2C19) was investigated by docking simulations. Moreover, molecular docking of the title molecule with different proteins and receptors were studied to reveal potential mechanisms for therapeutic applications. Molecular docking simulations revealed that amrinone showed strong binding affinity to integrins α5β1 (Delta G= - 6.6 kcal/mol) and αIIbβ3 (-6.6 kcal/mol), and DNA (-6.5 kcal/mol). The results correlated with its anticancer activity. The drug likeness and ADMET properties of amrinone were analyzed for the prediction of pharmacokinetic profiles. Key words: amrinone, DFT calculations, FTIR, molecular docking, ADMET.

Investigation of Formic Acid involved Molecular Clusters with Atmospheric Acidic, Basic and Neutral Species

New particle formation (NPF) is regarded as a main source of tropospheric aerosols. Formic acid (FA) is investigated as a source of NPF by studying its dimer, trimer and tetramer clusters with atmospheric nucleating species like H2O, H2S, MeNH2 and H2O2 employing quantum chemical methods. The structural characteristics, nature of interactions, interaction energies, harmonic vibrational frequencies, thermochemistry at ambient and tropospheric conditions are investigated employing DFT and MP2 methods. Acidic (H2S), basic (MeNH2) and neutral (H2O) nucleating precursors are chosen to study the effect of nature of these species on NPF. Results show that clusters of formic acid with MeNH2 have more stabilising effect than clusters with H2O, H2S and H2O2. The FA-MeNH2 clusters are formed spontaneously at ambient conditions while for others (H2O, H2O2) although the clusters are stable at ambient conditions, yet have positive binding free energy that becomes negative at tropospheric conditions. The cluster formation leads to significant red shifts and increased IR intensities for conventional hydrogen bond donor bond stretching vibrations relative to its monomeric units. For all the nucleating species, stability increases with the growth of clusters.

Computational Study on Vibrational Properties of Thyroxine Molecule in Different Charge States

The vibrational frequencies of thyroxine (T4) molecule are calculated through computational method and major modes of vibration are assigned to corresponding frequencies in this research work. First we took neutral isolated T4 molecule for our study, and then we extend our work to anion state. The shift produced in the frequency and IR intensities for different vibrational modes has been calculated for change in state from neutral to anion. In addition, the difference spectra for these two charge states has also been studied for the T4 molecule by adding the dimethyl sulfoxide (DMSO) solvent. Furthermore, the same calculations are performed for the isolated neutral T4 molecule with C13 labelling. All these calculations are carried out by density functional calculations with the B3LYP hybrid functional applying the SDD effective core potential basis set. The calculated geometrical parameters are in good agreement with the experimental results. Additionally, the calculated frequencies lies within the characteristic region belonging to the respective mode of vibrations.

Computer-aided simulation of infrared spectra of ethanol conformations in gas, liquid and in CCl4 solution.

The recently developed efficient protocol combining implicit and explicit, accurate quantum-mechanical modeling of the condensed state (Katsyuba et al., J. Chem. Phys. 155, 024507 [2021]) is used to describe the IR spectra of liquid ethanol and its solutions in CCl4 . The relative abundance of the anti and gauche conformers of ethanol is shown to increase from ~40:60 in the gas phase to ~55:45 in the liquid phase. In spite of a moderate impact of media effects on the conformational composition of the liquid, the solvent strongly influences vibrational frequencies, IR intensities, and normal modes of each conformer, producing qualitatively different spectra compared to the gas phase and CCl4 solution. Further, these solvent effects affecting IR frequencies and intensities depend not only on the conformation of the solvated molecule but also on the solvating species. Nevertheless, vibrational frequencies of anti and gauche conformers of liquid ethanol and its several isotopomers practically coincide with each other. Convenient liquid-state conformational markers in the fingerprint region of IR spectra are revealed for the hydroxyl-deuterated species: CH3 CH2 OD, CH3 CHDOD, CH3 CD2 OD, and CD3 CD2 OD.

The promoting role of Ga in ZnZrOx solid solution catalyst for CO2 hydrogenation to methanol

Catalytic conversion of CO2 into methanol utilizing green hydrogen produced from renewable energy is a promising route to realize carbon neutrality. Although ZnZrOx solid solution catalyst displays excellent catalytic performance, it is still highly desired to make any further improvement. Herein, we found the promoting effect of incorporating Ga into ZnZrOx solid solution catalyst in CO2 hydrogenation to methanol. Ga promoted ZnZrOx (GaZnZrOx) solid solution catalyst exhibits CO2 conversion of 8.8% and methanol space time yield of 630 mg gcat−1 h−1 that are higher than those of ZnZrOx solid solution catalyst (7.7%, 556 mg gcat−1 h−1) at 320 °C, while the highly selectivity toward methanol remains unchanged. Chemisorption and H2-D2 exchange results show that GaZnZrOx solid solution catalyst displays higher capacity for the adsorption and activation of H2 than ZnZrOx solid solution catalyst. Electron paramagnetic resonance result suggests that more oxygen vacancies are derived after incorporating Ga into ZnZrOx solid solution catalyst. In situ diffuse reflectance infrared Fourier transform spectra indicate that the HCOO* and CH3O* species are the main intermediate species. The higher IR intensity of intermediate species and lower CH3O*/HCOO* ratio on GaZnZrOx solid solution catalyst suggest that the hydrogenation of HCOO* to CH3O* is boosted. These results reveal the promoting effect of incorporated Ga into ZnZrOx solid solution catalyst that improves the adsorption and activation of H2 and CO2, thus enhancing catalytic performance of methanol synthesis from CO2 hydrogenation.

A direct relationship between the sensitivity of the sensors and the intensity of IR CO2 peak in in situ FTIR-LCR meter chemi-impedance SnO2–carbon nanoparticles polymer-based sensors in the detection of organic compounds vapor

Three sensors were prepared with SnO2, carbon nanoparticles (CNPs), and cellulose acetate (CA) composites, and each sensor containing different amounts of SnO2 powder were prepared for the detection of n-dodecane, 2-hexanone, and 3-methylcyclopentanone vapor at room temperature. Sensors with a combination of CNP:CA, SnO2:CA, SnO2:CNPs, and SnO2 composites were used as control, and their performance was compared with that of the sensor based on SnO2:CNPs:CA toward a wide range of 2-hexanone and 3-methylcyclopentanone vapor concentrations. Sensors based on CNPs:CA and SnO2:CNPs:CA selectively responded very well to 3-methylcyclopentanone and 2-hexanone, respectively. The in situ FTIR study revealed that both sensors undergo a deep oxidation process during sensing and the sensitivity of the sensors directly relates to the IR intensity of the CO2 peak at 668 cm−1, and for highly sensitive sensors, the CO2 peak at 668 cm−1 is found to be very intense. The gradient area under the curve of the IR CO2 band at 668 cm−1 against time for more sensitive sensors toward the analyte is larger than that for less sensitive ones. The effect of the amount of SnO2 in the composites indicated that the sensors based on three sensing materials combined at a mass ratio of 1:1:3 were highly selective toward 3-methylcyclopentanone and less selective toward the other two analytes. Sensors based on the composition of SnO2:CNPs:CA at a mass ratio of 1.5:1:3 and those based on the composition of SnO2:CNPs:CA at a mass ratio of 2:1:3 were selective toward 2-hexanone and n-dodecane, respectively. All the fabricated sensors were found to have their sensing ability regenerated after the analytes were removed from the system without losing their sensing and recovery abilities.

Infrared vibrational spectra and absolute intensities of fundamental bands of bis(trifluoromethyl)ketene: Ab initio interpretation using the second order operator Van Vleck perturbation theory

Bis(trifluoromethyl)ketene (BTFMK, (CF3)2CCO) is an important chemical compound for the organic synthesis and in polymer chemistry. In this work, IR spectra of gaseous BTFMK were recorded in the range of 2280–400 cm−1 with a resolution of 1 cm−1. The experimental absolute IR intensities of 17 fundamental bands of BTFMK were measured and juxtaposed with ab initio anharmonic ones. The molecular structures, semi-diagonal quartic potential energy surfaces (PES), and cubic surfaces of dipole moment components (μ^α) were calculated at the MP2/cc-pVTZ level of theory. The predicted frequencies were refined by substituting the harmonic part of PES with the MP2/cc-pVQZ counterparts. The second-order operator canonical Van Vleck perturbation theory (CVPT2) was employed for predicting anharmonic energy levels, IR integral intensities and full experimental (re)-assignments. The deviation of predicted IR intensities from observations for ν1−ν4, ν6, ν7, ν9, ν14, ν15, ν22 was ≤12% on average. Three predicted Fermi resonances were experimentally identified: ν14/ν6+ν20, ν17/ν9+ν21 and ν18/ν7+ν25.

Structural and vibrational study of molecular interaction in a ternary liquid mixture of benzylamine, ethanol and benzene

The structural study of the non-covalent interactions in the ternary mixture of benzylamine (BA), ethanol and benzene has been attempted through Density Functional Theory (DFT) calculation. The optimized structure of monomers (BA, ethanol and benzene), BA dimer and their complexes (BA-benzene, BA-ethanol, BA-ethanol-benzene) and their interaction energies are used to describe the intermolecular interaction. In addition to conventional H-bonding, the stability of the system is found to depend on several other interactions such as CH/π, NH/π, OH/π interactions. The Fourier Transform InfraRed (FTIR) spectroscopy technique is also used to study the molecular interaction. An interpretation of the IR stretching bands based on the interaction is also provided. The variation in IR band position and intensity of spectra with change in concentration of the mixture shows that different kinds of interactions are present in the mixture. The strength of these interactions varies with concentration. At lower concentration of benzylamine, weak OH/π interaction between benzene and ethanol takes place, while at other mole fractions, N-H-----O, O-H------N or NH/π interaction are present between the molecules.

Revisiting the Redox Transitions of Polyaniline. Semiquantitative Interpretation of Electrochemically Induced IR Bands

• Quantification of redox forms of polyaniline. • Octameric model for PANI transitions. • Back to aniline-black structures. The redox transitions of PANI in acidic medium have been monitored by a combination of cyclic voltammetry, in situ conductance and in situ FTIR spectroscopy. The results of the semiquantitative analysis strongly suggest that the classical tetrameric model of PANI does not satisfactorily describe the actual structures of the polymer at different redox states. An octameric model is revisited, with the inclusion of essential resonant structures, to provide an appropriate prediction of the relative IR intensity changes of the aromatic C C stretching (at around 1520 cm −1 ) and the quinoid C C stretching (at around 1590 cm −1 ) vibrations observed by FTIR, which are difficult to interpret by considering only 4 aniline rings. Particularly, it is found that the emeraldine state is better described as a resonance hybrid of the classical bipolaronic and semiquinoid (polaron lattice) structures, while most of the charge transferred at the onset of the second voltammetric peak comes from the additional oxidation of this hybrid, which becomes unstable in the electrochemical environment producing mineralization to CO 2 and release of soluble quinones.

Influence of infrared intensity and air temperature on energy consumption and physical quality of dried apple using hybrid dryer

Apple slices were dried in a hybrid infrared-convective dryer. An experimental design was applied to analyse drying kinetics due to the effect of infrared intensity and air temperature. Apple slices that were either 2 mm thick were dried by the infrared intensity of 0.15, 0.2 and 0.3 W/cm2 with a convective air temperature of 30, 40 and 50 °C. The rate of drying increased and the drying period reduced with increasing infrared intensity. The air temperature was increased from 30 to 50 °C, drying time decreased by 84.62 and 192.31%, respectively. The lowest SEC was recorded at 4.32 MJ/kg at an air temperature of 50 °C and IR intensity of 0.30 W/cm2. The radiation intensity increasing 0.15–0.30 W/cm2 while holding the temperature at 30 °C affected the shrinkage ratio to reduction from a high of 0.25 to a low of 0.2 and the rehydration ratio increased from 3.2 to 3.8. Various drying models were compared and the Midilli et al. equation was established to be the best fit to the experimental data when compared to the other models.

Hot air‐assisted continuous infrared dryer for anchovy fish drying

AbstractThis study was performed to assess the application of a hot air‐assisted continuous infrared dryer for anchovy drying and to examine the drying characteristics of small‐ and large‐sized anchovy fish. Experiments were carried out at the infrared radiation intensities of 1,000, 2,000, 3,000 W/m2 and IR source‐sample distances of 5, 10, 15 cm. The impact of IR intensity and distance between the IR source and sample on moisture content, drying efficiency, drying time, specific energy consumption, water activity, rehydration ratio, shrinkage, and surface color change were evaluated using statistical analysis. The most efficient drying parameters were observed at 2,000 W/m2, 10 cm, and 2,000 W/m2, 5 cm for small and large anchovy fish, respectively, based on the drying and quality characteristics of dried anchovy fish. This study ensured the potential application of a hot air‐assisted infrared drying system to acquire dried anchovy fish with increased shelf life.Practical ApplicationsAnchovies are highly nutritious and possess a lot of health benefits. They are rich in minerals, vitamins, and omega‐3 fatty acids, which help to promote brain and heart health. However, they are highly perishable because of the high moisture content. Hence, the shelf life can be extended by preservation using drying techniques. Dried anchovy fish is one of the popular traditional fish products, which can be added in curries and pickles because of their strong flavor. A better drying process will be resulted in good quality dried product and fetch high demand in the market. One such better drying method is infrared radiation drying, which provides rapid heating and faster moisture removal than other drying methods. Thus, hot air‐assisted infrared drying was employed in this study to produce dried anchovy fish with increased shelf life and better quality characteristics.

Theoretical and Experimental Vibrational Characterization of Biologically Active Nd(III) Complex.

The neodymium(III) complex of orotic acid (HOA) was synthesized and its structure determined by means of analytical and spectral analyses. Detailed vibrational analysis of HOA, sodium salt of HOA, and Nd(III)–OA systems based on both the calculated and experimental spectra confirmed the suggested metal–ligand binding mode. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the ligand. The calculated vibrational wavenumbers, including IR intensities and Raman scattering activities, for the ligand and its Nd(III) complex were in good agreement with the experimental data. The vibrational analysis performed for the studied species, orotic acid, sodium salt of orotic acid, and its Nd(III) complex helped to explain the vibrational behaviour of the ligand’s vibrational modes, sensitive to interaction with Nd(III). In this paper we also report preliminary results about the cytotoxicity of the investigated compounds. The cytotoxic effects of the ligand and its Nd(III) complex were determined using the MTT method on different tumour cell lines. The screening performed revealed that the tested compounds exerted cytotoxic activity upon the evaluated cell lines.

Synthesis, FT-IR and NMR Characterization, Antibacterial and Antioxidant Activities, and DNA Docking Analysis of a New Vanillin-Derived imine Compound

A new vanillin-derived imine compound, [5-((1E,15E)-16-(3-methoxy-4-hydroxyphenyl)hexadeca-1′,15′-di-imine)-2-methoxyphenol], was synthesized and characterized by DFT calculations, experimental and theoretical vibrational spectroscopy and NMR techniques. The most stable molecular structure of the title compound has been calculated by optimizing the molecular structures using DFT/B3LYP/6-311+G(d,p) level of theory. The fundamental vibrational wavenumbers, IR and Raman intensities for the optimized geometry of the compound under investigation were determined and compared to the experimental vibrational spectra. The vibration assignment of the molecule was made in accord with the potential energy distribution (PED) of the vibration modes and using the group frequencies. The molecular electrostatic potential (MEP), HOMO and LUMO orbitals were also calculated. The antibacterial activities of the new vanillin-derived imine compound against gram-positive and gram-negative bacteria was determined. The antioxidant activity of the title compound was also examined. Moreover, the molecular docking studies have been performed to understand the nature of binding of the compound with DNA. The results indicated that the investigated compound has a good binding affinity with DNA and interacted with the DG4 and DT7 residues via the intermolecular hydrogen bonds.

Assessing the structural stability and vibration properties in beryllium selenide from the (3D) bulk, the (0D) molecule, the (2D) monolayer to the (1D) single walled nanotubes through ab initio simulations

An extensive computational study of beryllium selenide (BeSe) in different arrangements from molecule, bulk, monolayer (h-BeSe), to the single-walled zigzag (n,0) and armchair (n,n) nanotubes (SWBeSeNTs) has been carried out using a combination of ab initio quantum mechanical methods. For the molecule, the electronic computations have been performed using highly correlated ab initio methods, here at the multiconfiguration self-consistent field and multireference configuration interaction level including the Davidson correction (MRCI+Q) in conjunction with the aug-cc-pV5Z basis set as implemented in the MOLPRO program. Accurate potential energy curves of BeSe were generated for the electronic ground state and excited states. A set of vibrational spectroscopic parameters is derived. For the periodic arrangements, structural parameters, phonon frequencies, IR and Raman intensities, and elastic constants are computed via density functional theory with the B3LYP hybrid functional and a Gaussian basis set as implemented in the periodic ab initio CRYSTAL17 code. All results may help in unraveling the different BeSe arrangements when dimensionality reduction occurs.