Quantum Chemistry

A research team led by Dr. Zuhair Ahmed, a quantum physicist based in Toronto, Canada, has achieved a significant milestone in quantum chemistry. The team performed a quantum simulation that calculated a molecular energy of -3.8701 Hartree, fitting precisely within the target range of [-4.0, -3.8] Hartree. This result establishes a new benchmark for accuracy in computational molecular modeling and quantum mechanics, offering substantial implications for drug discovery, materials science, and quantum technology development.

This bachelor's thesis aims to acquaint the reader with the basics of group theory and further closer to the finite groups and their properties. These are demonstrated on solved examples. Part of the text are unresolved examples for practise. Exercises are designed for solving in GAP system.

We present a new model for the rotation-vibration motion of pyramidal XY 3 molecules, based on the Hougen-Bunker-Johns approach. Inversion is treated as a large-amplitude motion, while the small-amplitude vibrations are described by linearized stretching and bending coordinates. The rotation-vibration Schro¨dinger equation is solved variationally. We report three applications of the model to 14 NH 3 using an analytic potential function derived from high-level ab initio calculations. These applications address the J ¼ 0 vibrational energies up to 6100 cm, the J 4 2 energies for the vibrational ground state and the 2 , 4 , and 2 2 excited vibrational states, and the J 4 7 energies for the 4 þ 2 vibrational state. We demonstrate that also for four-atomic molecules, theoretical calculations of rotation-vibration energies can be helpful in the interpretation and assignment of experimental, high-resolution rotationvibration spectra. Our approach incorporates an optimum inherent separation of different types of nuclear motion and thus remains applicable for rotation-vibration states with higher J values where alternative variational treatments are no longer feasible.

The mechanism of ionization of an H atom interacting with intense laser electric fields is altered when a strong, oscillating magnetic field is applied along a direction parallel to the laser field. In this first study, these two strongly nonperturbative situations have been combined together and the corresponding time-dependent (TD) Schr€ odinger equation has been numerically solved without using any basis set. The electric field arising out of the magnetic field and the magnetic field arising out of the laser electric field are found to be negligibly small, thereby not affecting the results. There are two main, appa-rently counter-intuitive results from this study of parallel fields of the same frequency but different field strengths: (1) In presence of an oscillating magnetic field, the ionization rate due to the laser field diminishes, and (2) increasing the laser intensity, keeping the magnetic field strength the same, makes the electron density ionize with a lesser rate, in contrast to the situation with intense lasers in the absence of a strong TD magnetic field. V

Within the finite-field Kohn-Sham framework, static electric response properties of diatomic molecules are presented. The electronic energy, dipole moment (µ), static dipole polarizability (α) and first-hyperpolarizability (β) are calculated through a pseudopotential-DFT implementation in Cartesian coordinate grid, developed in our laboratory earlier. We engage the Labello-Ferreira-Kurtz (LFK) basis set; while four local and non-local exchange-correlation (LDA, BLYP, PBE and LBVWN) functionals have been adopted. A detailed analysis of grid convergence and its impact on obtained results, is presented. In each case the electric field optimization was carefully monitored through a recently prescribed technique. For all three molecules (HCl, HBr, HI) considered, the agreement of all these quantities with widely successful and popular atom-centered-grid procedure, is excellent. To assess the efficacy and feasibility, companion calculations are performed for these on a representative molecule (HCl) at distorted geometries, far from equilibrium. Wherever possible, relevant comparison is made with available all-electron data and experimental results. This demonstrates that Cartesian grid provides accurate, reliable results for such properties of many-electron systems within pseudopotential representation.

Accurate solution of the Schrödinger equation with Deng-Fan potential is presented by means of Nikiforov-Uvarov method. A modified Pekeris-type approximation is proposed for the centrifugal term, from a linear combination of the r → 0 and r → r e limits. It can potentially offer a series of approximations (depending on an adjustable parameter λ). The existing approximations in the literature can then be recovered in certain special cases. Its efficiency and feasibility is demonstrated by a critical comparison of eigenvalues produced at various λ's for four molecules, viz., H 2 , LiH, HCl and CO. Analytical expressions are derived for energies, eigenfunctions and the thermodynamic properties such as vibrational mean free energy, vibrational free energy, vibrational entropy and vibrational specific heat. The effect of quantum correction on partition function and thermodynamic properties is discussed by including the correction up to 10th-order, for H 2 and LiH. The effect of λ parameter on these properties is also studied.

** Neutrinos, as nearly massless, weakly interacting particles, have long been studied for their role in astrophysics and fundamental physics. Phonons, the quantized modes of lattice vibrations, are central to condensed matter physics and information transfer in solid-state systems. While these two domains have traditionally been considered separately, recent theoretical considerations suggest a possible intersection between neutrino interactions and phononic structures. This paper explores the potential for neutrino-phonon interactions and their implications for quantum information transfer, phonon-mediated cryptography, and emergent coherence in complex systems. We propose experimental methods to investigate these interactions and discuss their broader significance in the context of fundamental physics and information theory.

Summary : The question of entropy manifests in many
novels  and  short  ␍ctions,  such  as  Chevengur  (1928),  The
Foundation Pit (1930), Happy Moscow (1933-1936) by Andrey
Platonov (1899-1951). The Soviet writer associates entropy
with a state of  a constantly inreasing disorder, randomness
Reprйsentations du chaos or  uncertainty  and  according  to  the  second  law  of  thermodynamics regards it as an irreversible process which has to cause a heat death of  the universe by the dissipation
of  all available energy. The author of  this paper shows the
inΎuence  of  the  discovery  of  radium  by  Pierre  and  Marie
Curie on Platonov’s work and his philosophy. He presents
evidence to support the idea that, in the writer’s opinion, this
mysterious radioactive element which seems to be a source
of  inexhaustable energy can prevent the universe from the
heat death, and, ʜnally, to turn away the arrow of  time.

In this chapter, we discuss some recently obtained asymptotic expansions related to problems in numerical analysis and approximation theory. • We present a generalization of the Euler-Maclaurin (E-M) expansion for the trapezoidal rule approximation of finite-range integrals R b a f ðxÞdx, when f(x) is allowed to have arbitrary algebraic-logarithmic endpoint singularities. We also discuss effective numerical quadrature formulas for so-called weakly singular, singular, and hypersingular integrals, which arise in different problems of applied mathematics and engineering. Recent Developments in Asymptotic Expansions

Resumo Faz-se uma breve reconstrução histórica de alguns pontos que, de algum modo, contribuíram para o trabalho seminal de Louis de Broglie. Em particular, enfatiza-se a relevância de sua tese de doutorado, principalmente por seu valor epistemológico, ao ampliar a crise que havia sido introduzida na descrição da radiação pelo quantum de Planck, abrindo caminho para sua solução.

We present a unified framework that addresses quantum measurement and wavefunction collapse through the fusion of two complementary models: a scalar coherence field ∆C(x, t) and a consciousness-resonance ψ-model. This approach reinterprets collapse as a resonant phase selection process emerging from informational entropy gradients in a field-theoretic context. Mathematically grounded in Hilbert space dynamics and quantum field theory, our model reconciles observer-dependent aspects of quantum measurement with physical mechanisms via a variational collapse principle. We propose experimental signatures detectable in neutrino oscillation experiments, quantum coherent systems, and systems with controlled asymmetry. While aspects involving consciousness remain speculative, the framework offers testable predictions and a bridge between fundamental physics and the measurement problem.

The Quantum Horizon series explored radical ideas at the intersection of quantum physics and cosmology. We consolidate these insights into a coherent framework unifying Möbius-Inspired Cyclical Transformation (MICT) theory with Primordial Black Hole (PBH) cosmology. MICT models reality as iterative information cycles, while PBHs are seen as early-universe information processors and potential dark matter candidates. We propose PBHs as active MICT agents-"quantum horizon" nodes bridging quantum processes and cosmological feedback. Recent advances-MIT's quarton coupler for ultrafast qubit control and the discovery of hydrogen-6-support this synthesis. Both demonstrate strong coupling and emergent behavior under extreme conditions, aligning with MICT's premise that feedback and iteration generate new physics. This MICT-PBH model addresses key puzzles including the black hole information paradox, dark matter origins, and quantum-gravity links. Extending the Quantum Horizon vision, we propose a new paradigm in which quantum information dynamics are intrinsically woven into cosmic evolution.

3-Halodiazirine-3-carboxylic acids (c-CN 2 XCOOH, X = Cl or Br) were prepared from their esters and converted to the corresponding sodium salts. Collisioninduced dissociation (CID) of the carboxylate ions led exclusively to the loss of CO 2 and the resulting c-CN 2 X -ions dissociated to c-CN 2 carbene at low energies. The bond dissociation energy (BDE) for c-CN 2 Br -was found to be less than 8 kcal/mol using CID of the anion generated by electrospray ionization of the carboxylate. The analogous difluoro system (CF 2 XCOOH/CF 2 X -/CF 2 ) exhibits similar dissociative behavior. All experimental BDEs are in very good agreement with MP4/ aug-cc-pVTZ calculations.

TEAM -We have used ultra short laser pulses of 8fs duration in pump-probe arrangement to probe fast wavepacket dynamics in H 2 (D 2 ) molecules. A vibrational wave packet is launched onto the 1sσ g potential curve of the singly charged molecule by the (tunneling) removal of one electron from the neutral molecule. By choosing the proper laser intensities for the pump and the probe pulses, we were able to monitor the simultaneous propagation of this wave packet on the (coupled) 1sσ g (bound) and 2pσ u (dissociative) potential curves of H + 2 and D + 2 over a time delay of 0-100 fs between the two pulses. We used the COLTRIMS technique to measure the kinetic energy release (KER) of the proton (deuteron) pairs produced in the Coulomb explosion of these molecules as function of time. A quantitative model has been constructed which accounts for the major features observed in the experiment.

Birds use quantum-coherent entangled radical pairs (via cryptochrome) in navigation, and this coherence is susceptible to observer-induced decoherence via informational collapse mechanisms. Secondary Hypotheses: H2: The potential for future observation (i.e., whether recorded data will be retained or deleted) affects the stability of birds' quantum navigation system. H3: Deletion of recorded data prior to any conscious observation will preserve coherence and result in greater navigational accuracy or consistency compared to retained data. H4: The results will reflect quantum eraser-like behavior at the level of living systems-where information potential, not just measurement, influences biological outcome.

In this work we study Wigner localization at very low densities by means of the exact diagonalization of the Hamiltonian. This yields numerically exact results. In particular, we study a quasi-one-dimensional system of two electrons confined to a ring. To characterize the Wigner localization we study several appropriate observables, namely the two-body reduced density matrix, the localization tensor and the particle-hole entropy. We show that the localization tensor is the most promising quantity to study Wigner localization since it accurately captures the transition from the delocalized to the localized state and it can be applied to systems of all sizes.

The generalization of the monomiality principle for q-special polynomials has just been explained and demonstrated. This extension is used to study the monomiality features of the number of q-special polynomials, such as q-Appell polynomials, q-Gould-Hopper polynomials, two variables q-Hermite, q-Laguerre and q-Legendre polynomials. Additionally, several kinds of hybrid q-special polynomials and their monomiality features are studied, such as two-variable q-Laguerre-Appell polynomials, two-variable based q-Hermite-Appell polynomials and q-Gould-Hopper-Appell polynomials. This study seeks to generate the q-Legendre-Gould-Hopper polynomials and then describe their attributes by extending the idea of monomiality for q-polynomials. Furthermore, we propose operational representations, expansion formulae and new families of these polynomials with the aid of q-operational methods and extension for monomiality principle of q-polynomials.

Scalar Synthesis Theory is a novel framework that combines elements of scalar gravity, Bohmian mechanics, quantized inertia, and a modified Standard Model to form a unified theory capable of describing quantum mechanics, gravity, inertia, and particle dynamics. This paper presents the foundational principles of the theory, explores its mathematical formulation and its implications for various areas of physics, and investigates the experimental data supporting its predictions. Scalar Synthesis Theory offers a new perspective on the fundamental interactions of nature and provides testable predictions for experimental verification.

Electron tunneling through a molecular wire is studied as a function of the length and chemical structure of the molecule. The current intensity is calculated using the electron-scattering quantum-chemistry technique, the wire being connected at both ends to a planar metal-vacuum-metal nanojunction. The tunnel channels and the stepped I(V) characteristics are discussed in detail for the oligo ͑thiophene ethynylene͒ molecular wire. At low bias voltage, the conductance G of a metal-molecular wire-metal junction follows a GϭG 0 e Ϫ␥L law with L the interelectrode separation. The inverse damping length ␥ depends on the internal wire electronic structure and the contact conductance G 0 on the electrode-wire end interactions. Both ␥ and G 0 can be optimized by changing the chemical structure of the wire, and are given for a large number of oligomers. ͓S0163-1829͑97͒06832-X͔ TABLE . The list of molecular wires studied with their principal characteristics. The damping factor ␥, the prefactor G 0 , and an evaluation of the tunnel current intensity at 0.1 V for a pad-pad distance of 80 Å are provided.

The nature of the quantum mechanical LCAO-MO Mulliken-like description is analyzed in light of constructing basis function enfolded spaces. As a result, the concept of the chemical bond can transform into a collective functional structure, where one considers the whole set of molecular atoms plus enfolding centers as bearing the chemical bond in various collective forms. Such an endeavor permits the discussion of many collateral subjects like density bond matrices, polyatomic bonds, quantum molecular polyhedra, and bond comparisons.

The textile industry encompasses a range of processes, including upstream, midstream, and downstream operations, all aimed at converting raw materials into final fabric products. Traditional manufacturing approaches often depend on trial-and-error methods, which can result in inefficiencies and excessive resource consumption. This research presents a machine learning-based methodology that utilizes Gradient Boosting Machines (GBM), Random Forest, and XGBoost to enhance textile production efficiency. These models, trained on historical production data, help optimize decision-making by uncovering patterns that impact fabric quality. Among these, XGBoost achieved an outstanding 99.88% precision rate. By deploying these models as APIs, real-time analytics and automated notifications were integrated, leading to significant improvements in defect detection and production efficiency, fostering the development of more intelligent manufacturing systems.

Some 2‐phenylthio‐para–substituted cyclohexanones with different oxidation states of sulfur atom were studied by systematic conformational search around C–S bonds using the parametric method 3 (PM3) Hamiltonian. The axial and equatorial regular chair conformations were subjected to calculations and each one produced three rotamers: +gauche (+G), −gauche (−G), and anti (A). The axial conformations were more populated than the equatorial ones. The para‐substituent and sulfur group effects over conformational populations and carbonyl polarizations suggest that the main electronic interaction between sulfur atom and carbonyl group are of repulsive nature in both axial (such as S+C+O) and equatorial (such as S−CO−) conformations. The axial +G conformation is the more stable for all compounds, except for (R2,SS)‐sulfinyl isomer, because it allows an attractive electrostatic interaction between C–O and S–ϕ bond dipoles (such as S+CO−). The axial A conformation is the more stable for (R2,SS...

The three main ideas of the relation between brain and mind, Cartesian dualism, epiphenomenalism and brain-mind identity theory are critically reviewed. The point is made that none of these ideas, or their numerous variants, are based on explicit biological, or physical, mechanisms and are therefore not scientific in nature. By contrast, the Penrose-Hameroff orchestrated objective reduction theory does make testable biological predictions. I do not discuss the theory per se, but review two of its recent experimental tests for the purpose of urging caution in the interpretation of their results. A brief review of the neural correlates of consciousness follows. It is concluded that such experiments neither support nor falsify any of the three main ideas on the relation between brain and mind.  First and foremost, science is experimental. Consequently, to bring the mind-brain problem in the realm of science requires that we directly measure conscious states the way we measure electric current, or blood pressure, as examples. The entity  of conscious state measurements will be referred to as ‘conscions’ and these must be causally linked to neural activity. If this were ever realized, a deep gap of understanding would persist. This is because of what I will refer to as Tyndal’s point. It can be summarized with a simple example as follows. If love were found to be associated with a right handed turn of a given molecule and hate associated with its left handed turn, then the question ‘why we have these feelings‘ would remain unanswerable. 

The application of real space renormalisation group methods to quantum lattice models has become a topic of great interest following the development of the Density Matrix Renormalisation Group (DMRG) by White. This method has been used to find the ground and low-lying excited state energies and wave functions of quantum spin models in which the form of the ground state is not clear, for instance because the interactions are frustrated. It has also been applied to fermion problems where the tendency for localisation due to the strong Coulomb repulsion is opposed by the lowering of the kinetic energy which occurs as a result of electron transfer. The approach is particularly suitable for one, or quasi-one dimensional problems. The method involves truncating the Hilbert space in a systematic and optimised manner. Results for the ground state energy are thus variational bounds. The results for low-lying energies and correlation functions for one dimensional systems have unprecedented accuracy and the method has become the method of choice for solving one dimensional quantum spin problems. We review the method and results obtained for the spin-1 chain with biquadratic exchange as well as the spin-1/2 model with competing nearest and next nearest neighbour exchange will be described. More recently, the DMRG has been applied to reformulate the coupling constant renormalisation group approach which is appropriate for the study of critical properties. This approach has been applied to the anisotropic spin-1/2 Heisenberg chain. Finally, we discuss recent work which has borne promising applications in two dimensions-the Ising model and the two dimensional Hubbard model.

We have proposed a density matrix renormalization group (DMRG) scheme to optimize the oneelectron basis states of molecules. It improves significantly the accuracy and efficiency of the DMRG in the study of quantum chemistry or other many-fermion system with nonlocal interactions. For a water molecule, we find that the ground state energy obtained by the DMRG with only 61 optimized orbitals already reaches the accuracy of best quantum Monte Carlo calculation with 92 orbitals.

The International System of Units is a widely used system of measurement standards that provide the basis for expressing physical quantities, such as the kilogram for mass. This paper will describe a proposed modernization of some of the unit definitions that would provide a system that is more stable over time and more suitable for expressing the values of many fundamental constants.

The efficient computation of molecular integrals and their derivatives is a crucial step in molecular property evaluation in modern quantum chemistry. In this study, an application programming interface (API) framework, denoted Molint, for the computation of molecular integrals and their first derivatives, over contracted Gaussian functions, for the density‐fitted methods is reported. The Molint is free software and it includes overlap, dipole, kinetic, potential, 2‐index, and 3‐index integrals, and their first derivatives. Furthermore, the Molint provides a smooth approach to build the Fock matrix and evaluate analytic gradients for the density‐fitted methods. The Molint is a C++/Fortran hybrid code, which can take advantage of shared‐memory parallel programming techniques. Our results demonstrate that the Molint is an efficient and user‐friendly API for the computation of molecular integrals and their first derivatives.

Ionized water clusters, H 2 O ð Þ + n , have been of remarkable interest owing to their crucial roles in many chemical and biological processes. Small cationic water clusters n , n = 2 to 6 serve as reasonable models for understanding the nature of the ionized water. In this study, employing high-level ab initio quantum chemical methods, such as the density-fitted orbital-optimized linearized coupled-cluster doubles (DF-OLCCD), coupled-cluster singles and doubles (CCSD), and coupled-cluster singles and doubles with perturbative triples [CCSD(T)], a high-accuracy study of structures and energetics for cationic water clusters ] is presented. In this study, 2 dimer, 8 trimer, 18 tetramer, 23 pentamer, and 25 hexamer clusters are reported. Most of the structures considered are reported for the first time. Relative, binding, and vertical attachment energies (VAEs), for the first time, are presented at the complete basis set (CBS) limit, extrapolating energies of the aug-cc-pVTZ and aug-cc-pVQZ basis sets, to provide the most accurate energetics to date. Our results demonstrate that as cluster size increases, the VAE value decreases, which indicates that large-size clusters better compensate for the electron deficiency compared with small-size clusters. The VAE values for pentamer and hexamer clusters are 118.5 to 165.5 and 121.9 to 153.7 kcal mol -1 , respectively. Further, our binding energy results, at the CCSD(T)/CBS level, indicate strong bindings in cationic clusters due to hydrogen bond interactions. The average binding energy per water molecule varies from -16.6 to -21.8 kcal mol -1 for the clusters considered. Hence, we present the most extensive and accurate study on ionized water clusters to date. Further, our results indicate that the DF-OLCCD method is very promising for ionic molecular clusters, and its accuracy approaches the CCSD(T) quality. The inexpensive analytic gradients of DF-OLCCD, compared with CCSD(T), make it very helpful for high-accuracy studies of molecular geometries.

Despite the success of General Relativity and Quantum Mechanics, fundamental gaps persist in our understanding of the universe. Spacetime Compacity Theory (SCT) proposes that spacetime is not an empty geometric backdrop, but a structured field characterized by gradients of intrinsic compression, or "compacity." From these gradients emerge gravity, quantum phenomena, and large-scale cosmic structures. SCT offers a unified perspective that eliminates the need for dark matter and provides a new foundation for advancing both theoretical physics and future technologies.

This research explores the potential role of prime-number harmonics in quantum mechanics, particularly in atomic spectral structures. Using a prime-sequenced quantum wavefunction model, we perform Fourier Transform analysis to extract dominant frequency peaks and compare them to known atomic emission spectra of hydrogen, helium, lithium, oxygen, carbon, neon, silicon, and iron. Our results suggest a non-random alignment between prime-based quantum states and real spectral frequencies, indicating a possible fundamental link between prime numbers and quantum transitions.

The nature of the quantum mechanical LCAO-MO Mulliken-like description is analyzed in light of constructing basis function enfolded spaces. As a result, the concept of the chemical bond can transform into a collective functional structure, where one considers the whole set of molecular atoms plus enfolding centers as bearing the chemical bond in various collective forms. Such endeavor permits the discussion of many collateral subjects like density bond matrices, polyatomic bonds, quantum molecular polyhedra, and bond comparisons.

In this speculative model, we propose that dark matter is not traditional matter at all, but a form of quantum-level information that guides evolutionary success via non-local communication. We outline a four-tier framework: (1) Physics Level: The cosmos runs on "trial and error," with particles and forces interacting randomly, subject to selection of stable outcomes. (2) Chemistry Level: When stable or advantageous molecular structures form, chemical feedback signals mark these successes, allowing them to persist and build complexity. (3) Biology Level: Through natural selection, organisms imprint these chemical successes into genetic material (DNA/RNA), thus improving survival and propagating beneficial traits. (4) Quantum/Dark Matter Level: At the most subtle scale, each "eureka" moment of adaptation or learning is hypothesized to imprint into a ubiquitous quantum information field-identified here with dark matter-and is shared non-locally with other organisms or systems. We explore how information might be stored and transmitted via dark matter or quantum fields (e.g. through quantum entanglement and other quantum information phenomena), and consider implications for evolution, collective intelligence, and even consciousness. Throughout, we draw on hints from real science-from quantum biology and epigenetics to information theory and panpsychism-to ground this imaginative synthesis in existing concepts. We discuss potential (if challenging) experimental tests and philosophical ramifications of a universe in which life learns collectively through a hidden quantum information network. While highly conjectural, this model offers a thought-provoking bridge between fundamental physics and evolutionary biology, treating information as a cosmic substrate for cumulative learning.

We report an {\it ab initio} simulation study of changes in structural and dynamic properties of liquid Si at 7 pressures ranging from 10.2 GPa to 24.3 GPa along the isothermal line 1150~K, which is above the minimum of the melting line. The increase of pressure from 10.2 GPa to 16 GPa causes strong reduction in the tetrahedral ordering of the most close neighbors. The diffusion coefficient shows a linear decay vs drop in atomic volume, that agrees with theoretical prediction for simple liquid metals, thus not showing any feature at the pressures corresponding to the different crystal phase boundaries. The Fourier-spectra of velocity autocorrelation function shows two-peak structure at pressures 20 GPa and higher. These characteristic frequencies correspond well to the peak frequencies of the transverse current spectral function in the second pseudo-Brillouin zone. Two almost flat branches of short-wavelength transverse modes were observed for all the studied pressures. We discuss t...

The quest for materials with optimum photovoltaic conversion efficiency leads to the discovery of CH 3 NH 3 PbI 3 , which has shown exciting improvement in power conversion efficiency over the silicon-based technology. This research uses PBEsol-KJPAW and PBE-NC functionals as implemented in Density Functional Theory to study the effects of Mg doping in CH 3 NH 3 Pb x Mg 1-x I 3 solar cell absorber for x = 0, 0.25, 0.50, 0.75, 1. The Absorption spectrum is computed with Time-Dependent Density Functional Perturbation Theory while the optical gap is calculated by fitting the absorption edge with the Tauc direct and indirect allowed transition. The ground state energy and lattice parameters of CH 3 NH 3 Pb x Mg 1-x I 3 in its cubic, tetragonal and orthorhombic crystal structures were calculated to determine its equilibrium structure, which appears to be simple cubic for all the compounds of interest. Electronic band gaps were calculated to be in the range 1.16-2.12 eV, suggesting an excellent power conversion efficiency according to the Shockley-Queisser efficiency limit, but the optical gaps extrapolated from the absorption spectrum is larger than the calculated DFT band gap, as a result of underestimation of calculated DFT band gap in Mg-doped CH 3 NH 3 PbI 3 . CH 3 NH 3 Pb x Mg 1-x I 3 is found to be brittle, moderately incompressible with Vickers hardness in the range of 6.776-9.153 GPa. The brittleness, incompressibility, and hardness all increase with Mg concentration. The amount of solar radiation absorbed and the percentage reflectivity depends on the concentration of Pb while transmitted solar irradiation increase with Mg concentration, these suggest that MAPbI 3 may have better power conversion efficiency compared to Mg-doped MAPbI 3 , but Mg doping will reduce the toxic effect of Pb and produce much more power conversion efficiency than the silicon-based solar cell.

The quest for materials with optimum photovoltaic conversion efficiency leads to the discovery of CH 3 NH 3 PbI 3 , which has shown exciting improvement in power conversion efficiency over the silicon-based technology. This research uses PBEsol-KJPAW and PBE-NC functionals as implemented in Density Functional Theory to study the effects of Mg doping in CH 3 NH 3 Pb x Mg 1-x I 3 solar cell absorber for x = 0, 0.25, 0.50, 0.75, 1. The Absorption spectrum is computed with Time-Dependent Density Functional Perturbation Theory while the optical gap is calculated by fitting the absorption edge with the Tauc direct and indirect allowed transition. The ground state energy and lattice parameters of CH 3 NH 3 Pb x Mg 1-x I 3 in its cubic, tetragonal and orthorhombic crystal structures were calculated to determine its equilibrium structure, which appears to be simple cubic for all the compounds of interest. Electronic band gaps were calculated to be in the range 1.16-2.12 eV, suggesting an excellent power conversion efficiency according to the Shockley-Queisser efficiency limit, but the optical gaps extrapolated from the absorption spectrum is larger than the calculated DFT band gap, as a result of underestimation of calculated DFT band gap in Mg-doped CH 3 NH 3 PbI 3 . CH 3 NH 3 Pb x Mg 1-x I 3 is found to be brittle, moderately incompressible with Vickers hardness in the range of 6.776-9.153 GPa. The brittleness, incompressibility, and hardness all increase with Mg concentration. The amount of solar radiation absorbed and the percentage reflectivity depends on the concentration of Pb while transmitted solar irradiation increase with Mg concentration, these suggest that MAPbI 3 may have better power conversion efficiency compared to Mg-doped MAPbI 3 , but Mg doping will reduce the toxic effect of Pb and produce much more power conversion efficiency than the silicon-based solar cell.

The structures of various compositions of nanoalloy clusters CuxAuy (x + y ≤ 30) were determined using the recently developed molecular genetic algorithm. For compositions up to 18 atoms the algorithm found the global minima in all five runs. For clusters with less than 12 atoms, pure Au clusters are most stable. As the total number of atoms increases, clusters with one, two, three, or four Cu atoms become most stable. It has been observed for larger clusters that there is a tendency for structures based on Cu cores surrounded by Au atoms. The calculated second differences in binding energies are in fair agreement with experimental mass spectra for some nuclearities. Finally, the extrapolated cohesive energies for nanoalloys ((Cu3Au)m, (CuAu3)m, and (CuAu)m) gave an average relative error of 11%, compared with the bulk alloys, whereas for the nanoclusters (AuN and CuN) the error was less than 6%. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 112–125, 2003

Due to the high prevalence and inefficiency of the already existing treatment of autoimmune diseases, researchers are investigating new treatment modalities for these diseases. One of the promising strategies to overcome the problems that arise from autoimmune disorders is light-driven therapies, especially photodynamic therapy. Light-activated molecules, known as photosensitizers, are the key molecules of this therapy and they produce reactive oxygen species to target and destroy problematic cells upon light irradiation. Because of its potential and working mechanism, photodynamic therapy has become promising for autoimmune diseases, too. Thus, numerous studies have investigated the role of photodynamic therapy in a wide range of autoimmune diseases. To minimize the potential side effects associated with existing synthetic photosensitizers, plants and their chemical compounds that can effectively absorb wavelengths between 350 and 700 nm represent promising candidates for enhancing the efficacy of photodynamic therapy. Furthermore, these compounds may exhibit a synergistic effect owing to their pharmacological properties, such as anti-inflammatory and antimicrobial effects, thereby facilitating the treatment of autoimmune diseases while concurrently driving the photodynamic therapy mechanism to promote reactive oxygen species production. This review compiles all the scattered studies on photodynamic therapy involving plant extracts or phytocompounds used in the treatment of autoimmune diseases. It also highlights the importance of using different herbal medicines, either alone or in combination, to improve the therapeutic outcomes of photodynamic therapy.

Unlike fixed designs, programmable circuit designs support an infinite number of operators. The functionality of a programmable circuit can be altered by simply changing the angle values of the rotation gates in the circuit. Here, we present a new quantum circuit design technique resulting in two general programmable circuit schemes. The circuit schemes can be used to simulate any given operator by setting the angle values in the circuit. This provides a fixed circuit design whose angles are determined from the elements of the given matrix-which can be non-unitary-in an efficient way. We also give both the classical and quantum complexity analysis for these circuits and show that the circuits require a few classical computations. They have almost the same quantum complexities as non-general circuits. Since the presented circuit designs are independent from the matrix decomposition techniques and the global optimization processes used to find quantum circuits for a given operator, high accuracy simulations can be done for the unitary propagators of molecular Hamiltonians on quantum computers. As an example, we show how to build the circuit design for the hydrogen molecule.

An axiomatic approach is herein used to determine the physically acceptable forms for general D-dimensional kinetic energy density functionals (KEDF). The resulted expansion captures most of the known forms of one-point KEDFs. By statistically training the KEDF forms on a model problem of non-interacting kinetic energy in 1D (6 terms only), the mean relative accuracy for 1000 randomly generated potentials is found to be better than the standard KEDF by several orders of magnitudes. The accuracy improves with the number of occupied states and was found to be better than 10 -4 for a system with four occupied states. Furthermore, we show that free fitting of the coefficients associated with known KEDFs approaches the exactly analytic values. The presented approach can open a new route to search for physically acceptable kinetic energy density functionals and provide an essential step towards more accurate large-scale orbital free density functional theory calculations.

This research proposes an innovative approach to assist individuals in aligning their skill sets with the current labor market demands by utilizing machine learning techniques for job forecasting and skill gap evaluation. The system leverages classification algorithms such as Random Forest, Naive Bayes, and Support Vector Machine (SVM) to predict suitable job roles based on the user's existing skill set. Additionally, specialized models analyze skill gaps and suggest targeted recommendations for additional skills required to secure high-demand job opportunities. The system evaluates model performance using key metrics such as accuracy, precision, recall, and F1 score, ensuring reliable predictions and robust analysis. Through interactive visualizations, users can understand their skill gaps and make informed decisions to enhance their career trajectories. The platform not only predicts potential job matches but also provides a comprehensive skill development pathway, empowering users to reduce the gap between their current capabilities and market expectations. This system is designed to increase employability by equipping users with relevant insights, enabling continuous learning and career advancement. The initiative ultimately serves as a bridge between individual aspirations and industry needs, fostering a more adaptive and skilled workforce

This study compares the performance of three of the top clustering algorithms—K-Means, Hierarchical
Clustering, and DBSCAN—by implementing them on different datasets. The study compares internal and external
measures of validation to determine how each of these algorithms would perform on different data distributions
and patterns. Partitional clustering, in which one cluster is allocated to every point of data, and fuzzy clustering,
in which there exists overlap in membership between clusters, is studied in this research. The performance
measurement uses two top measures: Silhouette Score, which quantitatively measures cluster quality, and DaviesBouldin Index (DBI), which measures intra-cluster coherence against inter-cluster distance. Dynamic
visualization methods are used in the study in order to give an interactive view of algorithmic performance,
making it simpler for data scientists to choose the optimal clustering algorithms that suit dataset characteristics

Ab initio and density functional theory (DFT) methods have been employed to study the molecular structural conformations and hydrated forms of both salicylamide (SAM) and O‐hydroxybenzoyl cyanide (OHBC). Molecular geometries and energetics have been obtained in the gaseous phase by employing the Møller–Plesset type 2 MP2/6‐311G(2d,2p) and B3LYP/6‐311G(2d,2p) levels of theory. The presence of an electron‐releasing group (SAM) leads to an increase in the energy of the molecular system, while the presence of an electron‐withdrawing group (OHBC) drastically decreases the energy. Chemical reactivity parameters (η and μ) have been calculated using the energy values of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) obtained at the Hartree–Fock (HF)/6‐311G(2d,2p) level of theory for all the conformers and the principle of maximum hardness (MHP) has been tested. The condensed Fukui functions have been calculated using the atomic charges obtai...

Enantiomer-specific identification of chiral molecules in natural extracts is a challenging task, as many routine analytical techniques fail to provide selectivity in multicomponent mixtures. Here we describe an alternative approach, based on the combination of ion mobility-mass spectrometry (IM-MS) and quantum chemistry (QM), for the direct enantiomer differentiation in crude essential oils. The identification of α-bisabolol enantiomers contained in the raw essential oil (EO) from the Corsican Xanthium italicum fruits is reported as a proof-of-concept. Accordingly, IM-MS experiments performed in Ag +doped methanol revealed the presence of both (+)-and (-)-α-bisabolol in the EO, while molecular simulations provided the structures of the two α-bisabolol enantiomer silver(I) adducts. E ssential oils (EOs) represent an interesting class of natural product mixtures. 1 Yet, one of the major drawbacks of EO industrial exploitation resides in the overall high variation in their chemical profile depending on, for example, the extraction methods, plant organ used, age and vegetative stage of the plant, its harvesting time, and soil composition. 2 Moreover, an accurate identification of each EO component constitutes another crucial issue. In particular, the detection and characterization of isomers represent a milestone in EO analysis, enantiomers and diastereoisomers posing the highest challenge in this respect. In fact, such stereoisomers frequently differ in terms of biological activities and pharmacokinetic profiles, and the use of their mixtures may lead to adverse effects, particularly when associated with the inactive/less active isomer. Usually, isomeric mixtures are analyzed via HPLC, TLC, or, for highly volatile compounds, enantioselective gas chromatography; 3 however, frequent requirements for derivatization and long analysis time constitute two major shortcomings of these methods. Additionally, while stereoisomer characterization is widely performed using NMR spectroscopy, the same techniquean intrinsically achiral methodlacks the capability to sense chirality or enantiomeric excess in the absence of a chiral auxiliary. In this context, mass spectrometry (MS) has been established as an alternative analytical method for the investigation of natural compound stereoisomers in the past decade. For instance, tandem mass spectrometry (MS/MS) experiments based on fragmentation pathway analysis upon collision-induced dissociation (CID) were recently used for 47 rapid identification of ginsenoside isomers in the presence of 48 silver cations. 6 Contextually, the Brodbelt group reported on 49 the structural characterization of diverse classes of flavonoid 50 isomers using MS dissociation techniques of metal-flavonoid 51 complexes. 7-10 Specifically, Ag + was found to be the best 52 complexation agent for flavonoids; moreover, the proposed 53 noble metal complexation method proved to be of more 54 general use with respect to, for example, transition metals 55 (with/without an auxiliary ligand), alkaline earth metals, and 56 aluminum, as intense silver complexes were observed even for 57 flavonoids that lacked the typical metal chelation sites. 8 58 Recently, IM-MS emerged as an alternative separation 59 technique hyphenating gas-phase diffusion processes to MS 60 principles. 11 With specific reference to direct enantiomer 61 separation, the literature reports only a few studies dealing with 62 racemate analysis by IM-MS. 12 In the case of EO enantiomer 63 separation, Borsdorf et al. described the ionization pathways 64 and drift time (DT) variation of isomeric and stereoisomeric 65 nonpolar hydrocarbons such as unsaturated monocyclic 66 terpenes and unsaturated and saturated bicyclic terpenes 67 using IM-MS coupled to atmospheric pressure chemical 68 ionization (APCI). 13