density functional theory (dft)

The investigation of adsorption behavior of Anastrozole on Poly (2-ethyl-2-oxazoline) surfaces can provide valuable information about its reactivity, electronic and structural properties of Poly (2-ethyl-2-oxazoline) in interaction with Anastrozole.The impacts of the estereoelectronic effect associated with donor-acceptor electron delocalization and dipole-dipole interactions on the structural and electronic properties and reactivity of Poly (2-ethyl-2-oxazoline) in interaction with Anastrozole was studied based on the Density Functional Theory (DFT) calculations by using the B3LYP/(6-31G*) level of theory in gas phase and water solution. In order to investigation of conductivity and electronic properties of Poly(2-ethyl-2-oxazoline) in the reaction with Anastrozole, the total electronic energy, dipole moment, orbital energies, charge density, density of state (DOS), LUMO-HOMO energy bond gaps, Adsorption energies (EAd), the global index includes hardness (η), electronegativity (χ), electrophilicity index (w), chemical softness (S) and electronic chemical potential (μ) were calculated. Thermodynamic functional analysis indicates that the relative energies (ΔE), free Gibb’s energies (ΔG) and enthalpies (ΔH) are negative for (Anastrozole – Poly (2-ethyl-2-oxazoline)) system but the calculated entropies (ΔS) are Positive, suggesting thermodynamic favorability for estereoelectronic interaction and loading of Anastrozole on polymer and these results confirm the structural stability of the Anastrozole – Poly (2-ethyl-2-oxazoline) in both gas and solvent phases. Delocalization of charge density between the bonding or lone pair and antibonding orbitals calculated by NBO (natural bond orbital) analysis.

This study employed advanced computational methods, including semi-empirical parametric method 3 (PM3) and density functional theory (DFT), to investigate the host/guest inclusion complexes of β-cyclodextrin (β-CD) with homovanilic acid (HVA). Utilizing B3LYP, M08HX, and PW6B95 approaches, global minima were optimized in both vacuum and aqueous phases. The focus spanned complexation, interaction, and deformation energies, as well as the geometry, electronic structure, and chemical reactivity of HVA during encapsulation. Natural-bonding orbital (NBO) simulations highlighted the significant role of intermolecular hydrogen interactions in the stability of HVA/β-CD complexes. The study, employing the Global-hybrid meta-GGA functional methodology (PW6B95/6-31G(d)), shed light on energetically favored molecules, emphasizing superior results in orientation A. The Gauge-Including Atomic Orbital (GIAO) method has been used to study 1H nuclear magnetic resonance (NMR) complexes. .These insights contribute to advancing host-guest systems and drug delivery applications.

The purpose of this computational study is to measure and evaluate the interaction of one of the important Parkinson's and influenza A drugs with different plate-like nanostructures.The interactions between the diamondoid amantadine molecule and nanosheets including graphene, boron-doped graphene (BC3), and aluminum, silicon, phosphorus and gallium doped BC3 have been studied using the B3LYP method with a basis set of 6-31G(d) by Gaussian software 09. A poor energy interaction between the amantadine drug molecule and the graphene nanoparticle was observed. The Ead (adsorption energy) and Eg (gap energy) of BC3 and Al-, Si-, P-, Ga-doped BC3 nanosheets with amantadine have been calculated. The results show that graphene nanosheets, BC3 and its types doped with the mentioned elements cannot be considered as a suitable sensor for the drug amantadine.

Cycloeucalenol (CEU) was the major composition of the Benue Propolis extracts identified via proton NMR. The corrosion inhibition behaviour of this extracts on carbon steel in 1.0 M HCl was investigated by using weight loss, electrochemical impedance spectroscopy, and computational methods. The results obtained revealed that the inhibition efficiency increased with an increase in inhibitor concentration, but decreased with increase in temperature. Impedance measurement showed that charge transfer was responsible for the corrosion process. The charge transfer resistance (R2) increased with concentration of the inhibitor as opposed to the double layer capacitance (Cdl) which decreased. The values of the Gibbs free energy (ΔG°) indicated a spontaneous adsorption of the extract components on the metal surface. The physically adsorbed propolis extract onto the carbon steel surface followed Langmuir adsorption isotherm model. The HOMO map shows the electron cloud situated in the C=C sp2 group, and then spread across the three consecutive cyclohexane rings and their substituents. From the Fukui function indices calculations, CEU is discovered to have its site for nucleophilic and electrophilic attacks each at one of carbon atoms of the alkene group in the molecule. The results have demonstrated that the composition of Benue propolis is active inhibitor of corrosion of carbon steel surface in HCl acidic medium.

In this study, the adsorption of para-chlorophenol on phosphorus-doped polypyrrole was investigated using density functional theory (DFT). Calculations are performed at two levels b3lyp/6-31+G(d, p) and wb97xd/6-31+G(d, p), for two orientations of adsorbate molecules. The correlation-exchange function wb97xd shows more negative adsorption energy for the adsorption of these compounds. Evaluation of energy level changes of HOMO and LUMO orbitals, hardness, chemical potential, softness, electrophilicity, diploe moment, charge transfer by Molliken method and natural bond orbitals (NBO), adsorption energy, the density of states (DOS) diagrams, molecular electrostatic potential (MEP), Intermolecular distances and analysis of non-covalent interactions (NCI) have been performed. Analysis of non-covalent interactions shows more van der Waals interactions between adsorbent and adsorbate in the wb97xd correlation-exchange function compared to b3lyp.

In the present study, the effect of transition elements on structural properties and electronic and linear optical and nonlinear optical (NLO) properties of fullerene C20 was studied by replacing the transitions elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn with one of the C20 carbon atoms at theoretical B3LYP/6-31+G(d) level. Frequency calculations for all optimized structures show no imaginary frequency which is the important evidence for their stability. It was observed as the result of the doping of transition metals the values of Eg (highest occupied molecular orbital–lowest unoccupied molecular orbital gap) was reduced which shows improving the electrical properties of the C20 by doping the transition metal atoms instead of one of the carbon atom. Additionally, transition metal doping in the C20 nanocluster enhances its dipole moment which the C19Sc nanocluster has the highest and the C19Cu has the lowest dipole moment. Finally, it has been demonstrated that in the presence of the first raw transition metal of periodic table in C20, the values of polarizability and first hyperpolarizability (α and β0) increases which the highest values of α and β0 was obtained via Sc and Mn atoms doping.

Phosphorene nanoribbon (PNR) is a two-dimensional crystalline substance possessing semiconductor property, which makes it a new promising gas sensor. The gas sensing performance significantly depends on the adsorption mechanism and the strength of bonding between gas molecules and phosphorene atoms. Adsorption of a gas molecule onto PNR can be investigated through different parameters, such as interatomic energy, distance between atoms, and changes in the band gap energy of PNR. In this research, first, the PNR relaxation is carried out for minimum energy of whole structure. Second, the folding and tubing of PNR are investigated for their stability and minimum energy specification. Next, we constructed a phosphorene nanotube (PNT) by connecting two folded PNR that we called it unconventional PNT (UPNT). We compared conventional cylindrical PNT (CPNT) with UPNT for their energies and electrical properties. In the final step, as gas nanosensor, the gas sensing behavior and specifications of CPNT and UPNT are investigated in the presence of several gases. Since a phosphorene nanotube generally has a stable structure, the presence of gas molecules causes deformation of crystalline of structure and change in its electronic properties. For evaluating the sensing properties of CPNT and UPNT, their I-V characteristics, density of states and energy band diagrams are calculated and compared in the absence and presence of gas molecules. The adsorption of CO, , , NH, and  gas molecules onto UPNT and CPNT are done in detail. The results show that the sensitivity of UPNT gas sensor is higher than that of CPNT for detecting special gas molecules. We further investigated the amount of charge transfer utilizing the nonequilibrium Green’s function (NEGF) formalism which is applied on crystallized atomic configuration.

In this study the effect of Li doping on the structural, electronic, and magneticproperties of Mn(N, As) compounds was investigated using the DensityFunctional Theory (DFT) with the Quantum ESPRESSO software. The effect of theLi impurity on the Mn(N, As) conduction behavior and physical characteristicssuch electronic band structure and density of states (DOS) were consideredand discussed simultaneously. The obtained results demonstrated that afterLi doping, the equilibrium lattice constant (a0) was decreased and the bandgap energy was increased. The electronic band structure and density of states(DOS) of the MnN compound showed the metallic and anti-ferromagneticcharacteristics while the MnAs compound exhibited the half-metallic andferromagnetic properties, however, by adding the Li impurity to these compounds,semiconducting and anti-ferromagnetic characteristics were observed. Moreover,the high spin configuration of the Mn atoms at the DOS profiles revealed thatthese two anti-ferromagnetic compounds might also be promising candidatesfor future magneto-electronic and spintronic devices such as resonant tunnelingmagnetoresistance, ultrafast and ultrahigh-density spintronic devices.

In this study, the adsorption hydroquinone on polypyrrole (ppy) adsorbents has been investigated using the density functional theory (DFT) method. Calculations were performed at two levels, b3lyp/6-31+G(d,p) and WB97XD/6-31+G(d,p). Studies were in the gas phase and water solvent with the conductive polarizable continuum model (CPCM) model. Evaluation of energy level changes of Homo and Lumo orbitals, hardness, softness, electrophilicity, dipole moment, charge transfer by Mulliken method and natural bonding orbitals, adsorption energy, density of states diagrams, molecular electrostatic potential, intermolecular distances and non-covalent interaction analysis has been performed.

In this contribution, density functional theory-based calculations have been carried out to assess the electronic, photocatalytic and optical properties of Ce1-xTixO2 system. Ti incorporation leads to a decrease of Ce 4f states and enhancement of Ti 3d states in the bottom of conduction band. Furthermore, it was found that doping ceria with Ti-like transition metals could evidently shift the absorption of pure CeO2 towards higher wavelength range. These findings can provide some new insights for designing CeO2-based photocatalysts with high photocatalytic performance. To the best of our knowledge, this investigation calculates Mullikan’s charge transfer of Ce1-xTixO2 system for the first time. Charge transfer reveals an ionic bond between Ce or Ti and O, and covalent bonds between Ce and Ti atoms in the studies systems.

In this research, the characterization of complexes [Pd(aemptrz)Cl2] (1), [Pd2(μ-mptrz)2(mptrz)2(en)].CH3OH (2) [Pd2(μ-mptrz)4] (3) and [Pd2(μ-mptrz)2(mptrz)2(en)] (4) (where aemptrz is 1‐(1‐(λ2‐azanyl)ethyl)‐4‐methyl‐5‐(λ1‐sulfanyl)‐4H‐1λ4,2,4‐triazole, en is ethylene diamine and Hmptrz is 4-methyl-4H-1,2,4-triazole-3-thiol) were carried out by Density Functional Theory (DFT) calculations. Structural, electronics and molecular properties (such as bond distances, bond angles, energies of highest occupied molecular orbital (EHOMO), the lowest unoccupied molecular orbital (ELUMO), the energy gap (ΔE), chemical hardness η, the dipole moment μ and Natural bond orbital (NBO) analysis of compounds) have been investigated using B3LYP/TZVP level of theory. Moreover, electronic structures of all complexes via NBO calculation show that Pd-N and Pd-S bonds are made of delocalization of occupancies from lone pair (LP) orbital of N, S atoms to the palladium atom. The FT-IR spectroscopy analysis and electronic spectra were calculated using B3LYP/TZVP basis set and compared with the experimental values. Furthermore calculation of vibrational spectra are also allocated based on the potential energy distribution (PED) using the VEDA 4 program. The electronic spectra were calculated using DFT and time dependent density functional theory (TD-DFT) methods.

Inhibitory activities of five derivatives of 1,2,3-triazole and isoxazole-linked pyrazole hybrids (A,B,C,D and D) were investigated on two bacteria cell lines E.coli (5R1R) and S.aureous (2XCT) to predict their potency and their use as antibacterial agents. Spartan’14 was used to optimized the compounds via Density functional theory to calculate the molecular descriptors of the studied ligands and a standard drug (Amoxicillin). All the ligands obey Lipinski rule except ligand E with higher molecular weight greater than 500g/mol. The band gap which explained the stability of the ligand-protein complex formed were observed to be lower than the standard with outstanding lower band gap from Ligand B and E, hence this two ligand is expected to have higher stability as compared to other ligands and the standard drug. The predicted affinities via docking studies for E.coli were -7.3kcal/mol, -8.5kcal/mol, -7.5kcal/mol, -7.9kcal/mol, -8.9 kcal/mol and S.aureous were -6.9kcal/mol, -7.8kcal/mol, -7.0kcal/mol, -7.5kcal/mol. -7.3kcal/mol for Ligand A, B, C, D and E respectively. Also a standard drug (Amoxicillin) was also subjected to docking studies with the two receptor. However, the two ligands gave better inhibition at the active site of the two protein as compared to the standard drug with higher affinities from Ligand B, D and E. In addition, ADMET properties of the ligands displayed that all the ligands could be better absorbed from the intestinal tract when administered orally with no toxicity and they are not easily undergo biodegradation. Therefore, the ligands are good drug candidate which could be considered for clinical trials.

In this work, the quantum mechanics calculations were carried out to elucidate the adsorption behavior of some corticosteroid drugs (clobetasol, beclometasone, prednisolone, and methylprednisolone) on the surface of C60 nano-fullerene using density functional theory (DFT) at B3LYP/6-31G (d,p) level. After optimization of the structures, various parameters such as HOMO and LUMO energies, energy gap, adsorption energy, cohesive energy, chemical hardness, chemical potential, dipole moment, electrophilicity index and changes in the length of some bonds data were calculated. The results showed that the amounts of energy gap and chemical hardness are decreased with binding of corticosteroids to fullerene, while those of chemical potential and electrophilicity index are increased. It means that nanocarrier increases the drug reactivity. Also, binding and stabilization energies are increased. The C60-Clobetasol, C60-Beclometasone, C60-Prednisolone and C60-Methylprednisolone presented the adsorption energy with the values of 54.3478, -6.5263, 45.1586, and 947.8854 KJ in gas phase, respectively. Moreover, the solubility of nanocarrier has increased in the water solvent compared to the gas phase. These results can be considered in pharmacy for these types of drugs and similar systems. The presence of oxygen atoms in the structure of drugs increases the ability of nano-fullerene as a drug carrier, because the ability of nitrogen atoms to protonation in acidic environment weakens their binding to fullerene in the target cell.

In this research, we investigated the interaction behavior of ornidazole drug on the surface of pristine as well as doped C60 fullerene with Si, B and Al using density functional theory (DFT) at B3LYP/6-31G* level in gas phase and water. To study ornidazole adsorption properties on the C60, we replaced a carbon atom with B, Si and Al atoms. After optimization of the structures, various parameters such as HOMO and LUMO energies, gap energy, adsorption energy, chemical hardness, chemical potential, dipole moment, electrophilicity index and thermodynamics data were calculated. In contrast to the pristine C60, the binding energy of ornidazole to the doped fullerenes is much more negative and the HOMO–LUMO gaps are significantly enlarged. Our results show that doping may improve C60 drug delivery properties.