Total Electronic Energy Research Articles

Polarization pinning at antiphase boundaries in multiferroic YbFeO3

Abstract The switching characteristics of ferroelectrics and multiferroics are influenced by the interaction of topological defects with domain walls. We report on the pinning of polarization due to antiphase boundaries in thin films of the multiferroic hexagonal YbFeO3. We have directly resolved the atomic structure of a sharp antiphase boundary (APB) in YbFeO3 thin films using a combination of aberration-corrected scanning transmission electron microscopy (STEM) and total energy calculations based on density-functional theory (DFT). We find the presence of a layer of FeO6 octahedra at the APB that bridges the adjacent domains. STEM imaging shows a reversal in the direction of polarization on moving across the APB, which DFT calculations confirm is structural in nature as the polarization reversal reduces the distortion of the FeO6 octahedral layer at the APB. Such APBs in hexagonal perovskites are expected to serve as domain-wall pinning sites and hinder ferroelectric switching of the domains.

Thawed Gaussian Wavepacket Dynamics with Δ-Machine-Learned Potentials.

A method for performing variable-width (thawed) Gaussian wavepacket (GWP) variational dynamics on machine-learned potentials is presented. Instead of fitting the potential energy surface (PES), the anharmonic correction to the global harmonic approximation (GHA) is fitted using kernel ridge regression─this is a Δ-machine learning approach. The training set consists of energy differences between ab initio electronic energies and values given by the GHA. The learned potential is subsequently used to propagate a single thawed GWP by using the time-dependent variational principle to compute the autocorrelation function, which provides direct access to vibronic spectra via its Fourier transform. We applied the developed method to simulate the photoelectron spectrum of ammonia and found excellent agreement between theoretical and experimental spectra. We show that fitting the anharmonic corrections requires a smaller training set as compared to fitting total electronic energies. We also demonstrate that our approach allows to reduce the dimensionality of the nuclear space used to scan the PES when constructing the training set. Thus, only the degrees of freedom associated with large-amplitude motions need to be treated with Δ-machine learning, which paves a way for reliable simulations of vibronic spectra of large floppy molecules.

Theoretical and experimental study of plasmon oscillation dispersion in Si and Ge crystals

Plasma fluctuation dispersion has been theoretically and experimentally studied in monocrystal samples of Si (111) and Ge (111). It has been shown that the dispersion depends on crystallographic orientations of materials under study. In this work, the dispersion effects in the CLEE spectra, which manifest themselves in bulk samples of Si and Ge, have been studied. The loss energy electron was studied by the CLEE method upon their reflection from Si(111) and Ge(111) at different angles of incidence of the electron beam on the surface. Calculation of the total electron energy loss with formula (5) shows that the form of the CLEE spectrum of primary electrons depends on the nature and magnitude of the electron density in a given direction and is in satisfactory agreement with the experimental data. Thus, the theoretical and experimental results show that in the case of single-crystalline Si and Ge, with increasing k, the values of the bulk plasma oscillation increase by 2–3 eV.

Effect of Metal Work Function on Electron Transfer Kinetics in Electrochemical Reactions

The longstanding problem of explaining the observed dependence of the kinetic rates of electrochemical reactions on the work function of the electrode material (metal) is revisited, based on a recent paper.1 It was proposed that this dependence could be explained in terms of the effect of the work function of the metal on the free energies of activation of the forward and backward electron transfer reactions. In this presentation, we will explore details of the proposed mechanism.In essence, the mechanism is based on the effect of work function on the Galvani potential of the metal at any given applied potential. Even though the total electron energy (Fermi level) of an electron in the electrode must be the same, regardless of the metal, when it is at equilibrium with a given electrolyte, the manner in which that energy is partitioned between the effect of work function and the effect of potential is significantly different for different electrode materials. A higher work function leads to more stabilization of an electron in the metal (lower free energy) and, since the total free energy must remain the same, this lower free energy due to work function must be compensated by a more negative Galvani potential.The classical analysis of the effect of a more negative potential is based on the theory that a change in potential has a greater effect on the initial (reactant) free energy than it does on the free energy of the transition state. Consequently, the activation energy of the forward (cathodic) reaction is decreased by some fraction α of the corresponding increase in electron energy in the metal. This type of analysis is generally used to quantify the effect of changes in applied voltage and derive current-voltage relationships. In this paper we extend the analysis to take account of changes in the (Galvani) potential ϕm of the metal due to changes in work function Φm.It is reasonable to assume that a change in ϕm will have a similar effect whether it occurs due to a change in applied voltage or due to a change in the work function of the metal. This implies that an increase in work function with a corresponding negative shift in Galvani potential can lead to a lowering of activation energy and so to faster kinetics. However, we must also consider a possible change in activation energy arising from the decreased electron energy (increased stabilization) due to higher work function. If this caused a change in activation energy it would be expected to be in the opposite direction to the change due to Galvani potential, since it would be expected to lower the initial free energy by a greater amount than that of the transition state.The presentation will consider in detail the interplay of these effects and the consequent implications for modelling electrode kinetics. K. S. R. Dadallagei, D. L. Parr IV, J. R. Coduto, A. Lazicki, S. DeBie, C. D. Haas, and J. Leddy, J. Electrochem. Soc. 170, 086508 (2023)

Investigating the optical properties and electronic structure of gallium phosphide nanotubes doped with arsenic via implementing first-principles calculations.

This study investigates the impact of arsenic doping on the optical characteristics and electronic structure of zigzag (8, 0) and armchair (4, 4) gallium phosphide nanotubes using first-principles calculations based on the GaP1-xAsx system, where x = 0, 0.25, 0.5, 0.75, and 1. The electronic calculations showed that doping more arsenic atoms reduces the energy band gap for zigzag and armchair GaPAs nanotubes. PDOS analysis indicates that Ga-4p and P-3p orbitals play a significant role in determining the electronic properties of the GaP nanotube. The dominance of Ga-4p and P-3p orbitals in both the valence and conduction bands indicates their importance across the energy spectrum of the material. The complex dielectric function and absorption coefficient of zigzag and armchair GaP1-xAsx nanotubes are calculated for incident radiation with energies ranging from 1 to 6.2eV. Optical results revealed that both zigzag and armchair GaPNTs exhibit strong absorption in the UV-visible regions due to electronic transitions between different Van Hove singularities. Also, due to quantum confinement effects, pure zigzag gallium phosphide nanotube exhibited two absorption edges at wavelengths (273 and 375nm). These edges stand from the energy level's quantization in the nanotube construction, affecting the absorption characteristics. Substitutional doping by arsenic atoms changes the absorption edge to the long wavelengths due to decreased bandgap energy. Investigating electronic structures and optical properties of nanotubes proposes several advantages, such as understanding the doping effects on the nanotube structure and contributing to the direction of the experimental studies. These computational studies play a key role in developing the applications of nanomaterials. Calculations of density functional theory (DFT) are achieved via the SIESTA package. SIESTA is a powerful and effective tool for executing DFT calculations on a large system of atoms. It generates numerous output files covering detailed information about the electronic structure, optical properties, total energy, optimized geometry, and other computed properties. The generalized gradient approximation GGA with Perdew-Burke-Ernzerhof PBE functional was used. A vacuum region of 10 A0 was applied to avoid the interactions of adjacent nanotubes.

Evolution of High-energy Electron Distribution in Pulsar Wind Nebulae

In this paper, we analyze the spectral energy distributions of 17 powerful (with a spin-down luminosity greater than 1035 erg s−1) young (with an age less than 15,000 yr) pulsar wind nebulae (PWNe) using a simple time-independent one-zone emission model. Our aim is to investigate correlations between model parameters and the ages of the corresponding PWNe, thereby revealing the evolution of high-energy electron distributions within PWNe. Our findings are as follows: (1) The electron distributions in PWNe can be characterized by a double power-law with a super-exponential cutoff. (2) As PWNe evolve, the high-energy end of the electron distribution spectrum becomes harder with the index decreasing from approximately 3.5 to 2.5, while the low-energy end spectrum index remains constant near 1.5. (3) There is no apparent correlation between the break energy or cutoff energy and the age of PWNe. (4) The average magnetic field within PWNe decreases with age, leading to a positive correlation between the energy loss timescale of electrons at the break energy or the high-energy cutoff, and the age of the PWN. (5) The total electron energy within PWNe remains constant near 2 × 1048 erg, while the total magnetic energy decreases with age.

Dynamical analysis of the low-temperature phase diagram of a cuprate superconductor

For a cuprate superconductor, specifically the yttrium barium copper oxide system, we analyze the low-temperature phase diagram consisting of the superconducting, pseudogap, and normal phases by using a phonon-mediated attraction and Coulomb repulsion mechanism. Through this analysis, we show this mechanism in the cuprate is quite important for its key dynamics. For the pairing mechanism, a variational method is developed and applied, and a generalized mean field theory is used to calculate the condensate energy and the energy gap of the quasiparticle. We obtain a self-consistent system of equations for these quantities. The superconducting and pseudogap phases, which involve pair-condensates, are assumed to be equilibrium systems of the condensate and normal subphases. The condition for the phase transition point is given by the equal total electronic energy gains. Assuming that the difference in the pairing range of the pair condensate is small between just above and below the transition temperature, computations are performed to solve the self-consistent system of equations. We find solutions compatible with experimental data. Plausible values of the energy gap in the superconducting phase and in the pseudogap phase are obtained. The present analysis shows that the phonon-mediated attraction and Coulomb repulsion mechanism itself is compatible with the experimental data. The importance of the screening effect through one-phonon exchange in the pairing mechanism and of the structure of the valence band is discussed.

Using small database and energy descriptors to predict molecular thermodynamic energies through mediated learning models

Delta machine learning (DML) models have paved a new way to obtaining high fidelity ab initio simulation results of materials by using quantities with lower computational cost as learning materials. However, the low out-of-sample extrapolative ability and the requirement of large training sets have limited broader applications of conventional DML models. In this work, we proposed the concept of non-trivial electron energy, an intermediary energy quantity decoded from the electron total energy but exhibiting high Pearson's correlation with various thermodynamic energies, to build up mediated machine learning (MML) models. By hybridizing the intermediary non-trivial electron energy (N) with a bond descriptor (B) and a spatial matrix (S) of organic molecules, our integrated NBS descriptor shows excellent predictive power of thermodynamic energies with errors close to 1 kcal/mol for MML models when trained by a database with 100 entries and tested by a database with 500 entries. Moreover, adding supplemental sets with 10 ∼ 20 entries into the original training set could greatly improve the out-of-sample extendibility of NBS MML models, such as the molecules with obviously larger size, with disparate bond-type, and even with different elemental compositions. The method of mediated learning provides alternative ways to breakthrough limitations of traditional DML models and can be applied conveniently to study formation enthalpy, thermodynamic energy barriers, multi-dimensional Gibbs free energy surface, and other quantum chemical quantities related to materials' internal energy, enthalpy, and free energy under various conditions at tunable training cost, prediction efficiency, and accuracy.

Electron acceleration in a warm, motional, magnetized plasma‐filled waveguide by twisted electromagnetic wave pulses

AbstractThis paper studies the acceleration of an electron in a magnetized plasma waveguide caused by the interaction between the twisted electromagnetic wave and the plasma wave in a motional plasma. The spatial dependence of the amplitude and phase of the twisted TM mode has been derived by solving the wave equation. With appropriately assigned initial values, total electron energy gain can be calculated using numerical calculations. Numerical results show that plasma motion, as long as the twisted electromagnetic wave pulse, significantly affects electron acceleration during an electron's passage through the waveguide.

Energy Decomposition Scheme for Rectangular Graphene Flakes.

We show-to our own surprise-that total electronic energies for a family of m × n rectangular graphene flakes can be very accurately represented by a simple function of the structural parameters m and n with errors not exceeding 1 kcal/mol. The energies of these flakes, usually referred to as multiple zigzag chains Z(m,n), are computed for m, n < 21 at their optimized geometries using the DFTB3 methodology. We have discovered that the structural parameters m and n (and their simple algebraic functions) provide a much better basis for the energy decomposition scheme than the various topological invariants usually used in this context. Most terms appearing in our energy decomposition scheme seem to have simple chemical interpretations. Our observation goes against the well-established knowledge stating that many-body energies are complicated functions of molecular parameters. Our observations might have far-reaching consequences for building accurate machine learning models.

STABILITY OF COBALT AND NICKEL COMPLEXES OF SUCCINIC AND MALEIC IONS STUDIED BY POTENTIOMETRIC TITRATION, UV-VIS SPECTROPHOTOMETRY AND QUANTUM CHEMICAL CALCULATIONS

In this study, composition and stability of coordination compounds of nickel (II) and cobalt (II) ions with succinate anion (L2-) and maleic anion (Y2-) in aqueous ethanol solutions with the molar concentration of ethanol ranging from 0.0 – 0.3 were studied by UV – Vis spectrophotometry at ionic strength of 0.1 maintained with sodium perchlorate. The result showed that, the formation of mono-ligand complexes of Ni2+ and Co2+ ions with succinate and maleic anions become stronger when the volume of ethanol rises. This may be due mainly to a change in the solvate state of the ligand with increasing ethanol concentration in the solvent. In all surveyed solvents, Co2+ forms less stable complexes than Ni2+ ion corresponding to the Irving-Williams series established for aqueous solutions. Obtained results were compared with literature data for akin compounds. The effect of solvent composition change on the geometry, charge, total electron and free Gibbs energies was studied using the DFT and MP2 levels of theory by using the Polarizable Continuum Model (PCM). The results obtained in this article by UV – Vis spectrophotometry and theoretical calculations were analyzed together with the potentiometric titration results obtained by us earlier for these complexes. The results of theoretical calculations are in good agreement with experimental data.

A Relationship between the Molecular Parity-Violation Energy and the Electronic Chirality Measure.

When the weak forces producing parity-violating effects are taken into account, there is a tiny energy difference between the total electronic energies of two enantiomers (ΔEPV), which might be the key to understanding the evolution of the biological homochirality. We focus on the electronic chirality measure (ECM), a powerful descriptor based on the electronic charge density, for quantifying the chirality degree of a molecule, in a representative set of chiral molecules, together with their EPV energies. Our results show a novel, strong, and positive correlation between ΔEPV and ECM, supporting a subtle interplay between the weak forces acting within the nuclei of a given molecule and its chirality. These findings suggest that experimental investigations for molecular parity violation detection should consider molecules with ECM values as large as possible and may support that a chiral signature is imprinted on life by fundamental physics via the parity-violating weak interactions.

Preparation of chlorophyll compounds and simulation of DFT optical properties assisted screening of photosensitizers from Ginkgo biloba leaves

Chlorophyll compounds (Chls) from Ginkgo biloba leaves (GBL) are non-toxic natural pigments characterized by highly conjugated molecules and special spectra, making them ideally potential photosensitizers (PSs) in photodynamics therapy (PDT). In this study, 4 Chls were isolated from Ginkgo biloba polyprenols (GBPPs) wastes by using silica gel column separation and high performance liquid chromatography (HPLC). In addition, two new chlorophyll derivatives were successfully synthesized with chlorin e6 as the primary raw material. To evaluate and identify superior chlorophyll PSs, Density Functional Theory (DFT) and Density Functional Theory (TD-DFT)were employed to decode the microscopic and spectral properties of Ginkgo biloba Chls (GBChls). The spectral absorption, optical stability and reactive oxygen species (ROS) production of GBChls were further analyzed through comparisons of their frontier molecular orbital layout, charge distribution and excitation energy properties. Our results show that about 63 % absorption in the Q band for 14 GBChls comes from the π⇢π* transition from the highest occupied orbital (HOMO) to the lowest unoccupied orbital (LUMO), indicating the favorable delocalization effect of these GBChls. In particular, those GBChls with the long chain of the phytyl group exhibited higher total electron energy and thus could significantly increase the light stability. However, the large spatial volume and hydrophobicity of these compounds with the phytyl group chain was unfavorable for cellular uptake, leading to low ROS in cells. The electronegativity of porphin macrocycles in GBChls positively correlates with the intracellular ROS production rate, meaning that the former likely promotes the energy transfer between PSs and molecular oxygen during type II photoreaction. Among the GBChls, chlorin e6 demonstrated the highest ROS yields in DMF, while purpurin 18 compounds displayed long-wavelength absorption (698 nm), strong Q-band absorption, good optical stability, and high intracellular ROS production. Our findings highlight that chlorin e6 and purpurin 18 are most potential PSs anticancer drugs and offer new research perspectives for the processing and utilization of GBL resources.

Calculation of the Electronic Properties Phthalocyanine (H2Pc), Silicon Phthalocyanine (Sipc), Phosphorus Phthalocyanine (PPc) and Energy Gap by the AM1 Method

Many semi-empirical methods are available in Gaussian 16. This patch enables analytical gradients and frequencies in addition to increasing efficiency by replacing the code from MOPAC open source, AM1 and PM3 technologies. In the case of a pure molecule, the values of total energy, bond energy, electronic energy, and nuclear energy (-170.893, -1496.855, -4332.708, 45) Kcal/mol have been successively added. After adding Si and P to the free Phthalocyanine molecule, the values transformed to (-133.30, -4987.486, -1294.027, 11.607) Kcal/mol. For the two resulting molecules (PcSi and PcP), the values became (-136.108, -4858.63, -9354.14, 79.930) Kcal/mol. Notably, the first number indicated an increase. Specifically, for total energy numbers, there was a decrease from -170.893 to -133.3 Kcal/mol when adding Si, and a decrease to -136.108 Kcal/mol when adding P. Overall, the energy value increased with both additions, but the bonding energy notably decreased with Si (-1496.855 to -4987.486 Kcal/mol) and P (-4858.63 Kcal/mol). Electronic energy increased from -4332.708 to -1294.027 Kcal/mol when Si was added. Nuclear energy decreased from 45.036 to 11.607 Kcal/mol when Si was added (increasing to 79.930 Kcal/mol with P). The Heat of Formation (H.o.F.) in Kcal/mol equaled 1565.04 when P was added, 1193.384 when Si was added, and 1531.528 when P was added again. The substantial impact of silicon on Phthalocyanine was evident. Furthermore, the dipole moment of the Phthalocyanine molecule, initially at D 3.687, decreased to D 2.093 and D 4.137 when Si was added first and P the second time, showcasing the significant impact of P due to its high atomic number. Determining the HOMO and LUMO and computing the values of Wavenumber, Wavelength, and Symmetry for the three molecules provided a clear illustration. The computation of electrical potential, electronic orbitals, and energy gap revealed an electronic density of 0.346 eV in the case of the free molecule H2Pc, 5.006 eV in the molecule PPc, and 5.660 eV in the case of SiPc. This offers a comprehensive understanding of the impact of adding P and Si to H2Pc.

Electron nonlinear dynamics in a compact accelerator based on the circular rotating TM110 mode

The present study investigates the electron autoresonant acceleration using the rotating transverse magnetic mode TM110 microwave field within an inhomogeneous magnetostatic field. Differential equations governing the evolution of the phase shift between the electron’s angular position and the angle at which transferred power is maximized, the total electron energy, and the longitudinal electron velocity are derived. Magnetic field profiles required to sustain electron acceleration are determined. The results demonstrate that an electron injected along the cavity axis with an energy of 30keV can be accelerated up to approximately 200keV, using an electric field amplitude of 20kV/cm, a frequency of 8GHz, and a linear magnetic field profile. Additionally, we consider the case of electron acceleration under exact resonance conditions, and the corresponding magnetic field profile predicted by the model is obtained.The findings presented in this paper are valuable for the design of RF accelerators utilizing the circular rotating TM110 mode, particularly in applications such as x-ray sources for medical purposes, airport security, and various other fields.

Quantum lattice dynamics and their importance in ternary superhydride clathrates

The quantum nature of the hydrogen lattice in superconducting hydrides can have crucial effects on the material’s properties. Taking a detailed look at the dynamic stability of the recently predicted BaSiH8 phase, we find that the inclusion of anharmonic quantum ionic effects leads to an increase in the critical dynamical pressure to 20 GPa as compared to 5 GPa within the harmonic approximation. We identify the change in the crystal structure due to quantum ionic effects to be the main driving force for this increase and demonstrate that this can already be understood at the harmonic level by considering zero-point energy corrections to the total electronic energy. In fact, the previously determined critical pressure of kinetic stability pkin = 30 GPa still poses a stricter bound for the synthesizability of BaSiH8 and similar hydride materials than the dynamical stability and therefore constitutes a more rigorous and accurate estimate for the experimental realizability of these structures.

PubChemQC B3LYP/6-31G*//PM6 Data Set: The Electronic Structures of 86 Million Molecules Using B3LYP/6-31G* Calculations.

The presented "PubChemQC B3LYP/6-31G*//PM6" data set is composed of the electronic properties of 85,938,443 molecules, encompassing a broad spectrum of molecules from essential compounds to biomolecules with a molecular weight up to 1000. These molecules account for 94.0% of the original PubChem Compound catalog as of August 29, 2016. The electronic properties, including orbitals, orbital energies, total energies, dipole moments, and other pertinent properties, were computed by using the B3LYP/6-31G* and PM6 methods. The data set, available in three formats, namely, GAMESS quantum chemistry program files, selected JSON output files, and a PostgreSQL database, provides researchers with the ability to query molecular properties. It is further subdivided into five subdata sets for more specific data. The first two subsets encompass molecules with carbon, hydrogen, oxygen, and nitrogen with molecular weights under 300 and 500, respectively. The third and fourth subsets incorporate molecules with carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur, fluorine, and chlorine, with molecular weights under 300 and 500, respectively. The fifth subset comprises molecules with carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur, fluorine, chlorine, sodium, potassium, magnesium, and calcium, with a molecular weight of under 500. The coefficients of determination for the highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap range from 0.892 (for CHON500) to 0.803 (for the whole data set). These comprehensive results pave the way for applications in drug discovery and materials science, among others. The data sets can be accessed under the Creative Commons Attribution 4.0 International license at the following web address: https://nakatamaho.riken.jp/pubchemqc.riken.jp/b3lyp_pm6_datasets.html.

Measurements of secondary electron emission yield in the linear plasma simulator BPD-PSI

The secondary emission properties of the surface play one of the key roles in its interaction with plasma. This paper presents the first study of electron-induced electron emission yield performed in the linear plasma simulator BPD-PSI. To verify the applicability of the measurement technique used, a series of experiments was conducted to investigate the total secondary electron yield as a function of the energy of primary electrons for several pure elements, such as carbon, copper, and tungsten. Particular attention was paid to the latter as one of the essential plasma-facing materials, due to its ability to withstand moderate plasma loads. The change in the total secondary electron yield of tungsten was studied in-vacuo after each subsequent change in its surface morphology as a result of: annealing at 2770 K, exposure to pure helium plasma at 1250 K and annealing of plasma-modified tungsten surface at 2770 K. The growth of nanoscale structures, known as fuzz, on its surface caused a reduction in the total yield of secondary electrons by 10–18% compared to the clean surface. A non-monotonic relationship between total secondary electron yield and primary electron energy was observed. The interpretation of this phenomenon is given in the present work.

Electronic and structural behavior of graphene and azulphene nanoflakes under the influence of two-point charges

We have studied the behavior of graphene and azulphene nanoflakes in the presence of two-point charges. The carbon systems geometry was optimized using the DFT method without symmetry constraint. We studied the coronene (7-ring), two azulphene-coronenes (7-ring) with different symmetries, the superbenzene (19-ring), and three azulphene-superbenzenes (19-ring) with also different symmetries and different combinations of five, six, and seven-member rings exposed to an electric field due to two-point charges. In addition, the induced electric dipole and quadrupole were studied as a function of the charge point magnitude and signs.The Stark-lo-Surdo effect in HOMO, LUMO, and total energies was analyzed. The positive (negative) charges decrease (increase) the HOMO, LUMO, and total electronic energies. The contraction and expansion of molecular systems and the induced charge in the molecular plane due to two identical charges were studied. Due to two identical charges, the null net force does not deform the molecular systems out-off the xy-plane at z = 0. Instead, the deformation occurs in the xy-plane at z = 0, and the positive (negative) identical charges expand (contract) the molecular systems. These systems suffer concavation under the presence of the electric field due to two-point charges with opposite signs. The central ring is closer to the positive charge, while the hydrogen atoms belonging to the edges are closer to the negative charge for curved graphene models. The concavation of azulene-based systems is irregular and very intricate.This work aims to generically describe the influence of a pair of ions on the energetic and structural (electronic and geometric) components of two-dimensional carbon nanosystems with five, six, and seven-member rings. Our studies allow understanding of the general behavior to extrapolate to other bidimensional systems with different charge exposition like ions. Despite the complexity of the performance of the electric field due to point charges to systems with many electrons, we can obtain some general behaviors, although difficult to interpret in some cases.

Assessment of the adsorption mechanism of amantadine drug onto pristine, Si- and Ge-doped Al12N12, and Al12P12 nanocages: A comparative DFT study

In the current study, the adsorption characteristics of pristine and doped (Si and Ge)- Al12N12 (AlN) and Al12P12 (AlP) nanocages towards the amantadine (AM) drug have been investigated in the gas phase by employing density functional theory (DFT). The study outcomes indicated that the amantadine drug interacts with the hexagonal ring of AlN and AlP nanocages through its H atoms and –NH2 group. The values of the adsorption energies on the pristine nanocages vary from −2.31 to −31.55 kcal/mol in the vacuum environment. However, after swapping out one of the central Al atoms with a Si or Ge atom, the adsorption energy of the doped AlN and AlP significantly increases towards the AM drug. From a thermodynamic perspective, the adsorption process of AM drug over Al12N12 and Al12P12 nanocarriers had a spontaneous and exothermic nature. The crucial and essential characteristics of the atoms in molecule (AIM) analysis, the negative and positive amounts of the total electron energy density and Laplacian parameters, respectively, illustrate that the examination interactions are a partial covalent nature. Charge transfer occurs from the AM molecule to the AlN and AlP nanocages, according to the Natural Bond Orbital (NBO) analysis. Taken altogether, these findings propose that the doped AlN and AlP nanocarriers are efficient aspirants for the development of the AM drug delivery process.