نتایج جستجو برای: density functional theory dft
تعداد نتایج: 1668215 فیلتر نتایج به سال:
We propose a density-functional theory (DFT) describing inhomogeneous polymer-carbon dioxide mixtures based on a perturbed-chain statistical associating fluid theory equation of state (PC-SAFT EOS). The weight density functions from fundamental measure theory are used to extend the bulk excess Helmholtz free energy to the inhomogeneous case. The additional long-range dispersion contributions ar...
Quantum chemical calculations at the B3LYP/6-31G* level of theory were employed for the structure-activity relationship and prediction of the antioxidant activity of edaravone and structurally related derivatives using energy (E), ionization potential (IP), bond dissociation energy (BDE), and stabilization energies (ΔE(iso)). Spin density calculations were also performed for the proposed antiox...
The geometrical frustration in the magnetic pyrochlore oxides causes interesting properties at low temperatures in these materials. Therefore, we studied two challenging materials, Er2Ti2O7 and Tb2Ti2O7, using an ab intio method, based on Density Functional Theory (DFT). To take into account the f electrons coulomb interactions correctly, we employed DFT+U, a Hubbard method correction. As spin-...
Because of the increasing interest in studying the phenomenon exhibited by charge-stabilized colloidal suspensions in confining geometry, we present a density functional theory (DFT) for a hard-core multi-Yukawa fluid. The excess Helmholtz free-energy functional is constructed by using the modified fundamental measure theory and Rosenfeld's perturbative method, in which the bulk direct correlat...
Using the Density Functional Theory (DFT) level by means of 3-21G, 6-31G and 6-31+G (d) basissets, the structural optimization of isolated Pyrazole and Pyrazoline was done in the gas phase. Then,the calculation about the solvent effect on the stability energies of Pyrazole and Pyrazoline wasperformed for the ten solvents using PCM model method at B3LYP/6-31+G(d) and then the dielectriceffects o...
The glass transition of a hard sphere system is investigated within the framework of the density functional theory (DFT). Molecular dynamics (MD) simulations are performed to study the dynamical behavior of the system on the one hand and to provide the data to produce the density field for the DFT on the other hand. Energy landscape analysis based on the DFT shows that there appears a metastabl...
We have investigated the electronic structure and thermodynamic properties of supercell of the -Al2O3 by first-principles calculation in framework of density functional theory (DFT) and full potential linearized augmented plane wave (FP-LAPW) with generalized gradient approximation (GGA) and by quasi-harmonic Debye model. Our calculated value for direct band gap of α-Al2O3 is 7.2 eV which i...
The complexes between C20 and C2 X4 , C2 X2 (X = H, F, Cl, Br) have been studied theoretically at the B3LYP/6-311G (d,p) level. The calculations include the optimized geometries, the interaction energies, aromaticity and thermodynamic. The interaction energies ranging from -60 to -101 kcal/mol and being ordered as: X = F> Cl > Br. Natural bond orbital (NBO) analysis has been performed on all ge...
The electronic and structural properties of pristine and carbon doped (C-doped) boron nitride nano-ribbons(BNNRs) have been studied employing density functional theory (DFT) calculations. Total energies, gapenergies, dipole moments, and quadrupole coupling constants (qcc) have been calculated in the optimizedstructures of the investigated BNNRs. The results indicated that the stability and gap ...
The relative stability of hydrogen-bonded of Molybdate-Phosphonic Acid (MPA) complex (1:2) ingas phase has been carried out using Density Functional Theory (DFT) methods. The methods are usedfor calculations are B3LYP, BP86 and B3PW91 that have been studied in two series of basis sets: D95**and 6-31+G(d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphorus. Predictedhydrogen-bond geom...
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