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On the basis of the generalized Poisson–Boltzmann equation derived from the Bogolyubov chain of equations for the equilibrium distribution functions in the pair correlation approximation, a general expression is proposed for the Helmholtz free energy of a system that contains any number of components and whose particles interact via arbitrary potentials. This opens up an extraordinary opportunity to simultaneously treat a whole range of physical effects including partial ionization, quantum effects of diffraction and electron degeneracy, short- and long-range interactions of charged particles with neutrals, finite size effects, etc. It is shown that all medium constituents are tied together in a single screening matrix, whose determinant and trace determine the excess contribution to the free energy. The approach developed is then applied to the problem of the ionization potential depression (IPD) leading to quite simple analytical expressions, which turn out to be useful for various practical purposes. In particular, for a single ionization from the neutral state the IPD is shown to significantly depend on the ionization degree such that it consists of the difference of charged and neutral contributions for a fully ionized plasma and turns non-zero for an almost neutral medium. On the other hand, for a multiple ionization process finite size effects of atoms and ions are demonstrated to be of great importance and accounted for in order to achieve good agreement with experimental data on the IPD under warm dense matter conditions.

In this work, we present an improved model for ionization potential depression (IPD) in dense plasmas that builds upon the approach introduced by Lin et al., which utilizes a dynamical structure factor (SF) to account for ionic microfield fluctuations. The main refinements include the following: (1) replacing the Wigner–Seitz radius with an ion-sphere radius, thereby treating individual ionization events as dynamically independent; (2) incorporating electron degeneracy through a tailored interpolation between Debye–Hückel and Thomas–Fermi screening lengths. Additionally, we solve the Saha equation iteratively, ensuring self-consistent determination of the ionization balance and IPD corrections. These modifications yield significantly improved agreement with recent high-density and high-temperature experimental data on warm dense aluminum, especially in regimes where strong coupling and partial degeneracy are crucial. The model remains robust over a broad parameter space, spanning temperatures from 1 eV up to 1 keV and pressures beyond the Mbar range, thus making it suitable for applications in high-energy-density physics, inertial confinement fusion, and astrophysical plasma research. Our findings underscore the importance of accurately capturing ion microfield fluctuations and electron quantum effects to properly describe ionization processes in extreme environments.

We theoretically studied and observed the photoionization rates of the alkali and noble atoms driven by an elliptically polarized Ti:sapphire laser for the barrier suppression ionization scheme. We extended the barrier suppression ionization formula developed by Posthumus and coworkers by considering the inclusion of the initial momentum of the ejected photoelectrons and the ponderomotive potential and Stark shift in unperturbed ionization potential. The extended formula is applied to both groups of atoms and the obtained results are compared with those obtained by the initial formula with the aim to determine the influence of all mentioned effects. Additionally, we explored the influence of the field’s ellipticity on the barrier suppression ionization rate. We found that it is sensitive to the change of the field ellipticity and the inclusion of all mentioned effects as well.

Herein, we report the synthesis of sulfur-substituted boron(III) subphthalocyanines (SubPcs) with cationic axial ligands. Subphthalocyanines were synthesized by a condensation reaction using the corresponding phthalonitriles and boron trichloride as a template. An aminoalkyl group was introduced on the central boron atom; this process was followed by N-methylation to introduce a cationic axial ligand. The peripheral sulfur groups shifted the Q band of SubPcs to a longer wavelength. The cationic axial ligands increased the polarity and enhanced the hydrophilicity of SubPcs. The effect of axial ligands on absorption and fluorescence properties is generally small. However, a further red shift was observed by introducing cationic axial ligands into the sulfur-substituted SubPcs. This change is similar to that in sulfur-substituted silicon(IV) phthalocyanines. The unique effect of the cationic axial ligand was extensively investigated by theoretical calculations and electrochemistry. In particular, the precise oxidation potential was determined using ionization potential measurements. Thus, the results of the present study provide a novel strategy for developing functional dyes and pigments based on SubPcs.

The vertical ionization potentials for systems of various sizes, ranging from simple molecules, DNA/RNA bases, donor and acceptor organic molecular systems as well as nanotubes are calculated using the ΔMP2-SCS family of methods [Śmiga et al 2018 J. Chem. Theory Comput. 14 4780-90]. We have shown that for all investigated cases, the ΔMP2-SCS methods, being almost cost free single-step post-Hartree-Fock calculation, provide very accurate vertical ionization potentials comparable in quality with state-of-art outer valence Green's function methods. Moreover, we show that a combination of the ΔMP2-SCS methods with the resolution of identity technique is effective and reliable an alternative to the semi-empirical density functional theory methods and Green's function-based calculations of ionization potentials for large molecular systems such as silicon-based or organic-based solar cells, for which the IP-EOM-CCSD calculations are too expensive for routine calculations.

Molecular hydrogen is the basis of hydrogen energy. It is formed and used in many fields of industry, physics, and chemistry. Molecular hydrogen is the main product formed during the gamma radiolysis of liquid cyclohexane. When studying the mechanism of molecular hydrogen formation during the gamma radiolysis of liquid cyclohexane, we found that the values of adiabatic electron affinity, one of the fundamental characteristics of atoms and molecules, had not yet been experimentally determined for hydrogen and cyclohexane molecules. Theoretical estimates of the adiabatic electron affinity of the hydrogen molecule made by other authors varied widely ([−0.3; −5.771] eV) and could not be compared with experimental values due to the absence of such data. Using DFT calculations at the PBE0/TZVPP level of theory, and a constructed correlation with experimental values of the adiabatic first ionization potential and electron affinity for a number of molecules, neutral radicals, and atoms, we estimated, for the first time, the experimental adiabatic electron affinities of hydrogen (−3.08 eV) and cyclohexane (−2.13 eV) molecules in the gas phase. When an electron is attached to a cyclohexane molecule, a cyclohexane radical anion is formed, a new, highly reactive species that has not been studied before. A new perspective on molecular hydrogen formation during the gamma radiolysis of liquid cyclohexane was introduced and discussed.

The nature of the influence of thermionic emission from a condensed phase on the concentration of ions in equilibrium thermal plasma has been studied using an analytical model. Spherical tungsten nanoparticles have been considered as a dust subsystem. It has been revealed that depending on the effective ionization potential of background gas atoms, two regimes of the charge state of the system are realized: with a positively and negatively charged dust component. It has been established that the size of nanoparticles affects the concentration of background gas ions in different ways under these regimes.

With the aim of choosing an appropriate standard for determining total phenol content (TPC) in food extracts, a theoretical study was done to demonstrate the electronic properties of nine phenolic compounds. Besides, TPC of three different tea extracts was determined by the Folin–Ciocalteu (F–C) assay with nine phenolic compounds as the standards. The frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and ionization potential (IP) of these standards were calculated with density functional theory. Results indicated the active sites of the nine standards by FMO and MEP. Moreover, the IP value of epigallocatechin gallate was about 15% lower than that of epigallocatechin, indicating that the 3-galloy group at C ring rendered a higher reactivity in the F–C assay. TPC of green tea measured by epicatechin was about 19% lower than that of gallic acid, suggesting that epicatechin was not an appropriate standard for tea extracts. It is deduced that gallic acid is a comparably good standard among commercial standards (relative standards). However, it is recommended that researchers should not choose a universal standard for all food extracts considering the heterogeneity and diversity of polyphenols in food extracts.

The structures and energetics of two dihydrochalcones (phloretin and its glycoside phlorizin) were examined with density functional theory, using the B3LYP, M06-2X, and LC- ω PBE functionals with both the 6-311G(d,p) and 6-311 + G(d,p) basis sets. Properties connected to antioxidant activity, i.e., bond dissociation enthalpies (BDEs) for OH groups and ionization potentials (IPs), were computed in a variety of environments including the gas-phase, n -hexane, ethanol, methanol, and water. The smallest BDEs among the four OH groups for phloretin (three for phlorizin) were determined (using B3LYP/6-311 + G(d,p) in water) to be 79.36 kcal/mol for phloretin and 79.98 kcal/mol for phlorizin while the IPs (at the same level of theory) were obtained as 139.48 and 138.98 kcal/mol, respectively. By comparing with known antioxidants, these values for the BDEs indicate both phloretin and phlorizin show promise for antioxidant activity. In addition, the presence of the sugar moiety has a moderate (0-6 kcal/mol depending on functional) effect on the BDEs for all OH groups. Interestingly, the BDEs suggest that (depending on the functional chosen) the sugar moiety can lead to an increase, decrease, or no change in the antioxidant activity. Therefore, further experimental tests are encouraged to understand the substituent effect on the BDEs for phloretin and to help determine the most appropriate functional to probe BDEs for dihydrochalcones.

In this work, we present a computational study on the antioxidant potential of myricetin 3,4 ′ -di- O - α - L -rhamnopyranoside (Compound M). A density functional theory (DFT) approach with the B3LYP and LC- ω PBE functionals and with both the 6-311G(d,p) and 6-311+G(d,p) basis sets was used. The focus of the investigation was on the structural and energetic parameters including both bond dissociation enthalpies (BDEs) and ionization potentials (IPs), which provide information on the potential antioxidant activity. The properties computed were compared with BDEs and IPs available in the literature for myricetin, a compound well known for presenting antioxidant activity (and the parent molecule of the compound of interest in the present work). Myricetin 3,4 ′ -di- O - α - L -rhamnopyranoside presented the lowest BDE to be 79.13 kcal/mol (as determined using B3LYP/6-311G(d,p) in water) while myricetin has a quite similar value (within 3.4 kcal/mol). IPs computed in the gas phase [B3LYP/6-311G(d,p)] are 157.18 and 161.4 kcal/mol for myricetin 3,4 ′ -di- O - α - L -rhamnopyranoside and myricetin, respectively. As the values of BDEs are considerably lower than the ones probed for IPs (in the gas phase or in any given solvent environment), the hydrogen atom transfer mechanism is preferred over the single electron transfer mechanism. The BDEs obtained suggest that myricetin 3,4 ′ -di- O - α - L -rhamnopyranoside can present antioxidant potential as good as the parent molecule myricetin (a well-known antioxidant). Therefore, experimental tests on the antioxidant activity of Compound M are encouraged.