Diatomic Potential Research Articles

Laser-Assisted Scattering With Screened Diatomic Potential

This study explores the differential cross section (DCS) for laser-assisted scattering of diatomic molecules, considering various polarization conditions (linear, circular, elliptical) and potential parameters. The primary objective is to understand how polarization, screening effects, and potential parameters influence the scattering behavior. Utilizing a model that incorporates the Morse potential with screening effects, the analysis treats the laser field classically as a time-dependent, spatially homogeneous electric field, while the electron dynamics are described quantum mechanically using the Schrödinger equation. The Volkov wavefunction is derived, and the first-Born S-matrix element is computed to evaluate the scattering process. The results show that the DCS decreases with increasing screening parameters, with linear polarization yielding higher values than circular or elliptical polarization. Specifically, at an initial momentum of 8 MeV and a final momentum of 9 MeV, the DCS for elliptical polarization is notably higher. The DCS also varies with potential strength and well width, showing a peak at 0.14 Å for potential well width. The findings suggest that linear polarization is most effective for scattering studies under varying potential strengths. It is recommended to focus on linear polarization for enhanced scattering efficiency and to carefully adjust screening parameters and potential well widths for optimal results.

Analytical potential energy functions for CO in its ground and excited electronic states.

Accurate functions to analytically represent the potential energy interactions of CO diatomic system in , , and electronic states are proposed. The new functions depend upon only four parameters directly obtained from experimental data, without any fitting procedure. These functions have been developed from the modified generalized potential proposed by Araújo and Ballester. The function for the electronic state represents a significant improvement to the previously proposed model. To quantify the accuracy of the potential energy functions, the Lippincont test is used. The novel potential was also compared with the classical Morse potential and with the recently proposed Improved Generalized Pöschl-Teller potential. Furthermore, the main spectroscopic constants and vibrational energy levels are calculated and compared for all potentials. The present results agree excellently with the experiment Rydberg-Klein-Rees (RKR) potentials. The rovibrational energy levels of the proposed diatomic potentials were asserted by solving radial the Schrödinger equation of the nuclear motion with the aid of the LEVEL program.

Performance characteristics of marine diatoms Cylindrotheca sp. and Trieres chinensis under nutrient limitation and their potency as feedstock for biodiesel production

Microalgae-derived biodiesel is commonly studied and recently gained attention as a possible substitute feedstock for production of biodiesel. In this study, the potential of marine diatoms, Cylindrotheca sp. (FPU 0031) and T. chinensis (FPU 0030), for production of biodiesel was evaluated by investigating the effect of nutrient limitation (100, 75, 50, and 25 % Roschin medium) on growth behavior response, lipid productivity, and FAME profiles of the diatom strains. The total lipid yield increased under nutrient-limited culture condition. When the concentration of the nutrient was restricted to 50 %, the average lipid yield of Cylindrotheca sp. and T. chinensis were 19.32 and 21.72 % with lipid productivity of 73.46 and 68.19 mg L−1 day−1, respectively. Nutrient limitation resulted in a decrease in biomass yield and an increase in the lipid yield of the diatom strains. The properties of biodiesel generated by the two diatoms were assessed based on FAME profiles using empirical equations. Results showed that Cylindrotheca sp. and T. chinensis conforms to the biodiesel standards specifications set by EN 14214 and ASTM D6751. The predicted properties of biodiesel observed for Cylindrotheca sp. and T. chinensis were both ideal, e.g. good cold filter plugging points (−6.94 °C and − 2.16 °C), cetane numbers (65.57 and 75.29), cloud points (1.81 °C and 7.75 °C), pour points (1.60 °C and − 4.86 °C), and low kinematic viscosities (2.89 and 2.16 mm2 s−1), respectively. Thus, suggesting the potential use of these diatoms as feedstock for producing biodiesel with high-grade fuel characteristics.

Effects of temperature on the growth, total lipid content and fatty acid composition of Skeletonema dohrnii

The potential of diatoms as aquatic bait, attribute to their abundance in highly unsaturated fatty acids, has been extensively studied. Temperature plays a crucial role in the synthesis of these fatty acids. This study specifically investigated the impact of temperature on the growth, total lipid content, and fatty acid composition of Skeletonema dohrnii, a planktonic diatom commonly associated with red tides and water blooms in China. The aim is to evaluate its suitability as an aquatic bait and provide insights for large-scale factory farming. Results indicated that the highest biomass and maximum growth rate occurred at 28°C, with no significant deviation from the control group at 25°C. At 28°C and 15°C, there was a significant increase in the total lipid content and the total fatty acid content, with a more pronounced effect at 15°C. At 28°C, EPA and DHA content measured at 0.97 ± 0.01 mg.DW.L-1 and 0.264 ± 0.01 mg.DW.L-1 respectively, surpass those at 15°C due to lower biomass. Conversely, at 15°C, substantial synthesis of long-chain polyunsaturated fatty acids, with EPA constituting up to 32.24 ± 0.24% of the total fatty acids, is observed. Modulating the temperature could optimize the utilization of S. dohrnii as an aquatic feed source. These findings underscore the potential of S. dohrnii as a high-quality aquafeed and lay the groundwork for its success in ocean warming scenarios.

Marine diatom algae cultivation in simulated dairy wastewater and biomass valorization.

Liquid byproducts and organic wastes generated from dairy processing units contribute as the largest source of industrial food wastewater. Though bacteria-mediated treatment strategies are largely implemented, a more effective and innovative management system is needed of the hour. Thus, the current study involves the cultivation of centric diatoms, Chaetoceros gracilis, and Thalassiosira weissflogii in simulated dairy wastewater (SDWW) formulated using varying amounts of milk powder with artificial seawater f/2 media (ASW). The results revealed that cell density and biomass productivity were highest in the 2.5% SDWW treatment cultures of both the strains, the maximum being in C. gracilis (7.5 × 106 cells mL - 1; 21.1mg L-1day-1). Conversely, the total carotenoid, chrysolaminarin, and phenol content were negatively impacted by SDWW. However, a considerable enhancement in the total lipid content was reported in the 2.5% SDWW culture of both species. Furthermore, the fatty acid profiling revealed that though the total polyunsaturated fatty acid (PUFA) content was highest in the control setups, the total mono polyunsaturated fatty acid (MUFA) content was higher in the 5% SDWW setups (30.66% in C. gracilis and 33.21% in T. weissflogii). In addition to it, in the cultures utilizing energy from external carbon sources provided by SDWW, the biodiesel produced was also enhanced owing to the heightened cetane number. Thus, the current study evidently highlights the organic carbon acquisition potential of marine diatoms with the scope of providing sustainable biorefinery.

Isolation and cultivation of freshwater diatom <italic>Nitzschia palea</italic> HY1 for increasing biomass and fucoxanthin production

Diatoms, a type of microalgae distributed worldwide, have been identified as potential sources of biomass, lipids, and high-value compounds. While marine diatoms have been extensively studied, the potential of freshwater diatoms still needs to be explored. In this study, a novel strain of freshwater diatom was isolated from the Jungnangcheon stream located in Seoul, Republic of Korea (37°33'08.0" N, 127°02'40.0" E). This newly isolated strain was classified through phylogenetic analysis, and its morphology was investigated using light and electron microscopy; it was named Nitzschia palea HY1. N. palea HY1 grown in freshwater media (FDM) produced higher biomass (0.68 g L<sup>-1</sup>) and fucoxanthin production (9.19 mg L<sup>-1</sup>) than in conventional diatom media. Furthermore, increasing the bicarbonate concentration from 2 to 10 mM enhanced the maximum biomass and fucoxanthin production in FDM by 2.7 fold and 1.5 fold, respectively. Remarkably, the introduction of aeration to the modified FDM (MFDM) led to a substantial increase in the maximum biomass and fucoxanthin production of N. palea HY1, exhibiting 3.8-fold and 4.1-fold enhancement, respectively, compared to FDM alone. These findings suggest that optimizing the cultivation of N. palea HY1 using MFDM could provide an alternative to marine sources for fucoxanthin production.

Thermal Responses and the Energy Spectral of Diatomic Molecules Using Nikiforov–Uvarov Methodology

The parametric Nikiforov–Uvarov approach and the Greene–Aldrich approximation scheme were used to achieve approximate analytical solutions to the Schrödinger equation, involving an interaction of the modified deformed Hylleraas potential mixed linearly with the improved Frost–Musulin diatomic molecular potential. For each ℓ-state, the energy spectra and normalized wave functions were generated from the hypergeometric function in the closed form. The thermal properties of such a system, including the vibrational partition function, vibrational mean energy, vibrational mean free energy, vibrational specific heat capacity, and vibrational entropy, were then calculated for the selected diatomic molecules using their experimental spectroscopic parameters. Furthermore, the peculiar conditions of this potential were evaluated, and their energy eigenvalues were calculated for the purpose of comparison. The acquired results were found to be in reasonable agreement with those reported in the literature.

Identification of diatoms from different rivers in Chhattisgarh

Diatoms are unique microalgae found in almost all water bodies. They are the only single-celled organisms with a siliceous cell wall or frustules and are ubiquitous in water bodies. Their presence and diversity make them valuable in forensic investigations, particularly in cases of drowning. Diatoms can serve as trace evidence by linking suspects to crime scene. The diversity of diatom species varies across different areas influenced by environmental factors and seasonal variations. Extensive research has been conducted on diatoms in various states of India, but the diversity of diatoms was not studied in the major rivers of the Chhattisgarh region. In this study, we aimed to address this gap by conducting a taxonomic analysis of diatoms and adding them to a new database. Samples were collected from different rivers in Chhattisgarh resulting in the identification of 34 diatom species. This study contributes to understanding diatom diversity in the region and enhances the forensic potential of diatoms in future investigations.

Topological effects on non-relativistic eigenvalue solutions under AB-flux field with pseudoharmonic- and Mie-type potentials

In this paper, we investigate the quantum dynamics of a non-relativistic particle confined by the Aharonov–Bohm quantum flux field with pseudoharmonic-type potential in the background of topological defect produced by a point-like global monopole. We solve the radial Schrödinger equation analytically and determine the exact eigenvalue solution of the quantum system. Afterwards, we consider a Mie-type potential in the quantum system and solve the radial equation analytically and obtain the eigenvalue solution. We analyze the effects of the topological defect and the quantum flux with these potentials on the energy eigenvalue and wave function of the non-relativistic particles. In fact, it is shown that the energy levels and wave functions are influenced by the topological defect shifted the result compared to the flat space results. In addition, the quantum flux field also shifted the eigenvalue solutions and an analogue of the Aharonov–Bohm effect for bound-states is observed. Finally, we utilize these eigenvalue solutions to some known diatomic molecular potential models and presented the energy eigenvalue and wave function.

Out-of-time-order correlator for the van der Waals potential

The quantum-to-classical correspondence is often quantified in dynamics by the out-of-time-order correlator (OTOC). In chaotic systems, the OTOC is expected to grow exponentially at early time, characteristic of a Lyapunov exponent; however, exponential growth can also occur for integrable systems. Here we investigate the OTOC for realistic diatomic molecular potentials in one degree of freedom, finding that the OTOC can grow exponentially near the dissociation energy of the molecule. Further, this dynamics is tied to the classical dynamics of the atoms at the outer classical turning point of the potential. These results should serve to guide and interpret dynamical chaos in more complex molecules.

Analytical Solutions of the Molecular Kratzer-Feus potential by means of the Nikiforov-Uvarov Method

The analytical methods for solving Schrödinger equation are essential and effective tools with which we can investigate the spectroscopic properties, the electronic structure, and the energetic properties of the diatomic molecules (DMs). Accordingly, in this work, we used the Nikiforov-Uvarov (NU) method to solve the three-dimensional nonrelativistic Schrödinger equation with the molecular Kratzer-Feus (KF) potential and obtain the exact analytical bound state energy eigenvalues as well as their corresponding normalized eigenfunctions. The effective KF diatomic molecular potential well is investigated and represented graphically for several well-known DMs. The bound state energy levels are tabulated numerically for arbitrary values of the vibrational and rotational quantum numbers. The results obtained in this work are found to be in excellent agreement with the already-existing results in the literature.

Efficient gene replacement by CRISPR/Cas-mediated homologous recombination in the model diatom Thalassiosira pseudonana.

CRISPR/Cas enables targeted genome editing in many different plant and algal species including the model diatom Thalassiosira pseudonana. However, efficient gene targeting by homologous recombination (HR) to date is only reported for photosynthetic organisms in their haploid life-cycle phase. Here, a CRISPR/Cas construct, assembled using Golden Gate cloning, enabled highly efficient HR in a diploid photosynthetic organism. Homologous recombination was induced in T.pseudonana using sequence-specific CRISPR/Cas, paired with a dsDNA donor matrix, generating substitution of the silacidin, nitrate reductase and urease genes by a resistance cassette (FCP:NAT). Up to c. 85% of NAT-resistant T.pseudonana colonies screened positive for HR by nested PCR. Precise integration of FCP:NAT at each locus was confirmed using an inverse PCR approach. The knockout of the nitrate reductase and urease genes impacted growth on nitrate and urea, respectively, while the knockout of the silacidin gene in T.pseudonana caused a significant increase in cell size, confirming the role of this gene for cell-size regulation in centric diatoms. Highly efficient gene targeting by HR makes T.pseudonana as genetically tractable as Nannochloropsis and Physcomitrella, hence rapidly advancing functional diatom biology, bionanotechnology and biotechnological applications targeted on harnessing the metabolic potential of diatoms.

Topological effects produced by point-like global monopole with Hulthen plus screened Kratzer potential on Eigenvalue solutions and NU-method

In this article, the approximate eigenvalue solution of the Schrödinger non-relativistic equation in 3D with a non-central potential of superposition of Hulthen potential and screened Kratzer potential in a point-like global monopole space-time is obtained. We employ a suitable approximation scheme like the Greene-Aldrich approximation in the centrifugal and reciprocal terms that appear in the radial equation and solve it using the parametric Nikiforov-Uvarov method. The results are analyzed for the topological defects and the magnetic flux and show that the eigenvalue solution gets modified in comparison to the flat space result with this superposed potential. Finally, we utilize the eigenvalue solution to some diatomic molecular potential models, such as screened Kratzer and Varshni potential and discuss the effects on the eigenvalue solutions.

Approximate eigenvalue solutions with diatomic molecular potential under topological defects and Aharonov-Bohm flux field: application for some known potentials

In this paper, we determine the approximate eigenvalue bound state solution of the radial Schrodinger equation in three-dimension in the presence of the Aharonov-Bohm flux field with two-term diatomic molecular potential in point-like global monopole (PGM) defect. We analyse the effects of factors, such as topological defects, background curvature associated with topological defects as well as the potential. We also show that the energy levels shift due to the presence of the magnetic flux which gives us an analogue of the Aharonov-Bohm effect for the bound state. Finally, we apply the quantum system for some known potential models, such as q-deformed Hulthen-type potential and Manning-Rosen potential, and discussed the effects of various factors on the eigenvalue solutions.

Reconciling spectroscopy with dynamics in global potential energy surfaces: The case of the astrophysically relevant SiC2.

SiC2 is a fascinating molecule due to its unusual bonding and astrophysical importance. In this work, we report the first global potential energy surface (PES) for ground-state SiC2 using the combined-hyperbolic-inverse-power-representation method and accurate ab initio energies. The calibration grid data are obtained via a general dual-level protocol developed afresh herein that entails both coupled-cluster and multi-reference configuration interaction energies jointly extrapolated to the complete basis set limit. Such an approach is specially devised to recover much of the spectroscopy from the PES, while still permitting a proper fragmentation of the system to allow for reaction dynamics studies. Besides describing accurately the valence strongly bound region that includes both the cyclic global minimum and isomerization barriers, the final analytic PES form is shown to properly reproduce dissociation energies, diatomic potentials, and long-range interactions at all asymptotic channels, in addition to naturally reflect the correct permutational symmetry of the potential. Bound vibrational state calculations have been carried out, unveiling an excellent match of the available experimental data on c-SiC2(A11). To further exploit the global nature of the PES, exploratory quasi-classical trajectory calculations for the endothermic C2 + Si → SiC + C reaction are also performed, yielding thermalized rate coefficients for temperatures up to 5000K. The results hint for the prominence of this reaction in the innermost layers of the circumstellar envelopes around carbon-rich stars, hence conceivably playing therein a key contribution to the gas-phase formation of SiC, and eventually, solid SiC dust.

Universal anharmonic potential energy surfaces for XY2-type molecules

An approach to generate anharmonic potential energy surfaces for both linear and bent XY2-type molecules from their equilibrium geometries, Hessians, and total atomization energies alone is presented. Two key features of the potential energy surfaces are that (a) they reproduce the harmonic behavior around the equilibrium geometries exactly and (b) they have the correct limiting behavior with respect to total bond dissociation. The potentials are constructed from two diatomic potentials, for which both the Morse or Varshni potentials are tested, and a triatomic potential, for which modified forms of the Anderson-n potential are tested. Potential energy surfaces for several linear and bent molecules are constructed from ab initio data, and the third-order derivatives of these surfaces at their equilibrium geometries are compared to the results of finite difference computations. For bent molecules, the vibrational spectra predicted by vibrational configuration interaction calculations on these surfaces are compared to experiment. A modified version of the Anderson-n potential, in combination with the Varshni potential, is demonstrated to predict vibrational frequencies associated with bond angle bending an average of 20 cm−1 below the harmonic oscillator approximation and with a fourfold reduction in the root-mean-square deviation from experiment compared to the harmonic oscillator approximation.

Potential parameters, ro-vibrational energy spectra, and expectation values of the improved deformed exponential-type potential

In this contribution, potential parameters were derived for the improved deformed exponential-type potential (IDEP) using Varshni conditions for a diatomic molecule potential. Expression for bound state ro-vibrational energies was obtained by solving the Schrödinger equation in the presence of the IDEP. In modeling the centrifugal term of the Schrödinger equation, a Pekeris-like approximation scheme was employed. Expectation values of potential and kinetic energies were obtained for the IDEP within the framework of Hellmann–Feynman theorem. The IDEP was used to model the spectroscopic data of four diatomic molecules, viz., ICl (X 1Σg+), NaK (c 3Σ+), O2+ (X 2Πg), and NaLi (A 1Σ+). The average absolute deviation from the dissociation energy obtained was 0.1235%, 0.9227%, 1.2275%, and 1.2651%, respectively. The results demonstrated that the IDEP was an ideal model for the diatomic molecules. Data obtained for expectation values of kinetic and potential energies showed that the total energy of the system was conserved and that at upper bound vibration quantum number, the energy of the molecules was entirely kinetic.

A semiempirical potential for alkali halide diatoms with damped interactions I. Rittner potential.

A new semiempirical potential is described for the ground state X1Σ+ of the alkali halide diatoms. The model potential is the first to account for the damping of all the electrostatic and induction potential terms as well as of the long-range dispersion potential. Accordingly, the potential does not have a negative singularity at vanishingly small internuclear distances and is the first Rittner-type model with a realistic dependence of the repulsion at short distances. The new potential is tested by comparing with ab initio potentials, which presently are only available in the well region for the molecules LiF, LiCl and CsI. The three parameters of the new potential are determined by fitting the latest experimental parameters for the well depth De, bond distance Re and vibrational frequency ωe. The new potential is in good agreement with the ab initio potentials.

Envisaging the role of pharmaceutical contaminant 17-β estradiol on growth and lipid productivity of marine diatom Chaetoceros gracilis

In the recent past, the presence of steroid hormones in marine bodies has led to the eruption of endocrine - disrupting molecules which have detrimental effects on aquatic life. However, the resilience and robustness of diatoms to adsorb and grow under the multitude of nutrient stress allow them to utilize the plethora of such compounds. Hence, in this study, we have implemented this unique ability of diatoms to sustain on simulated steroidal wastewater made of estradiol pills and analyze their corresponding impact on growth, biomass production, and lipid synthesis. We hereby report that with an increasing concentration of estradiol (0.5–2.0 mg L−1) there was an increment in cell numbers, and a 1.5-fold increase in the dry cell weight and lipid content (up to 29.5% DW). Thus, culturing Chaetoceros gracilis in the optimized media had a significant impact on biomass productivity which could further promote the untapped potential of diatoms.

Improved q-deformed Scarf II oscillator

In this work, the improved q-deformed Scarf II oscillator (IQSO) is formulated through the Varshni conditions for diatomic molecule potential. Equation for bound state energy eigenvalues of the IQSO is obtained by the SUSYQM method, a Pekeris-like approximation scheme is used to model the centrifugal term of the Schrödinger equation. Expressions for molar entropy and Gibbs free energy are deduced for the IQSO from equations of energy eigenvalues and partition function within the context of Poisson summation formula. The IQSO is used to model experimental Rydberg-Klein-Rees (RKR) data of six diatomic molecules including: KRb (B 1Π), CO+ (X 2Σ+), Cl2 (X 1Σg +), ICl (X 1Σg +), NbO (X 1Σ+), and K2 (X 1Σg +). The average absolute deviation and mean absolute percentage deviation are used as accuracy indicators. Computed data revealed that the IQSO is an excellent model in fitting the RKR data of the diatomic molecules examined in this work. Numerical values of molar entropy and Gibbs free energy calculated for ICl (X 1Σg +) molecule are almost indistinguishable from existing experimental data for gaseous ICl (X 1Σg +) molecules. This suggests that the IQSO is a near perfect model for representing the internal vibrations of the ICl (X 1Σg +) molecule.