Ab initio calculations

Ebook "A structural and vibrational study of the chromyl chlorosulfate, fluorosulfate, and nitrate compounds" presents important studies related to the structural and vibrational properties on the chromyl compounds based on Ab-initio calculations. The synthesis and the study of such properties are of chemical importance because the stereo-chemistries and reactivities of these compounds are strongly dependent on the coordination modes that adopt the different ligands linked to the chromyl group.

90p coduathanh1122 27-03-2024 3 1   Download

Part 1 book "Computational chemistry - Introduction to the theory and applications of molecular and quantum mechanics" includes content: An outline of what computational chemistry is all about, the concept of the potential energy surface, AB initio calculations, molecular mechanics, introduction to quantum mechanics in computational chemistry.

397p muasambanhan08 23-02-2024 6 1   Download

Hydrogen bonding on two-dimensional silicon carbide (2D SiC) was studied using molecular dynamics and ab initio calculations. By investigating a converged density functional theory (DFT) calculation, the stable bonding sites of a hydrogen atom on the 2D SiC were found at the top sites (TSi and TC, of which TSi is a more stable adsorption site).

8p vijeff 30-11-2023 3 2   Download

The structural, electronic, magnetic and optical properties of suggested XAlO3 (X = Cs, Rb and K) perovskites under pressure effects are investigated by means of the first-principles calculations with the technique of the Full Potential Linearly Augmented Plane Wave (FP-LAPW) implemented within Wien2k computer package.

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A first-principles approach is used to study the structural, electronic and magnetic properties of the Co2TaAl Heusler compound with CuHg2Ti-type structure. The investigation was done using the (FPLAPW) method where the exchange-correlation potential was calculated with the frame of GGA by Perdew et al. (Phys. Rev. Lett. 77 (1996) 3865).

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Over the last few years, the primary state of materials has been succesfully described via the use of a calculation method in physics - Ab initio calculations. In this paper, the results of the ab initio study on the bulk structure of iron nitride are presented.

6p vikoenigsegg 29-09-2022 10 3   Download

The molecular structure of bis(2‒isobutyrylamidophenyl)amine (H3 LNNN) has been determined from single‒crystal X-ray diffraction data. The crystal packing of H3 LNNN is governed by the N–H⋯O and C–H⋯O hydrogen-bonding and C–H⋯π stacking interactions between the vicinal molecules. The intermolecular interactions in the crystal structure of H3 LNNN have been also examined via Hirshfeld surface analysis and fingerprint plots. The Hirshfeld surface analysis showed that the important role of N–H⋯O and C– H⋯π interactions in the solid‒state structure of H3 LNNN.

33p langthannam 29-12-2021 7 0   Download

Using ab-initio calculations at the MP2/6-311G(3df, 2pd), a very high level theory, we obtained minimum energy structures for the C2H5O radical, products and transition states of reactions on the potential energy surface.

7p tamynhan9 02-12-2020 17 1   Download

In order to understand the photocatalytic mechanisms of N-doped TiO2 with different doping positions of N, this research performed ab-initio calculations based on density functional theory (DFT) without and with Hubbard U correction, concentrate on the electronic structure of the materials.

8p tamynhan9 02-12-2020 19 1   Download

This research performed ab-initio calculations to find the possible doped position of V atoms into the lattice of TiO2 anatase and compared that with experimental results. Calculated formation energies of un-doped and doped models prove that V atoms prefer to substitute into Ti positions rather than O positions or interstitial positions, in a good agreement with XPS results.

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In this research, ab-initio calculations have been used to study the geometry, electronic structures, adsorption energy and the formation of TiO2/Graphene hybrids. The unit cells of TiO2/Graphene have been built, optimized and calculated using GGA-PBE parametrization of exchange-correlation functional.

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Our study includes the optimization of the geometries, the calculation of the binding energies and relevant vibrational frequencies along with a natural bond orbital analysis including the charges on the different atoms, the occupation of selected antibonding orbitals and the hyperconjugation energies.

8p tamynhan8 04-11-2020 12 1   Download

The elastic constants and various optical properties of MnIn2S4 including the dielectric constant, absorption coefficient, electron energy loss function and reflectivity were calculated as a function of incident photon energy. Those results are discussed in this study and compared with available experimental results.

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This study investigates the adsorption mechanism of 2-butanone (ethyl methyl ketone) on the surface of graphene by using Density Functionals Theory (DFT). A 2-butanone molecule was chosen as a selected example of main volatile organic compounds (VOCs) in exhaled breath.

9p tamynhan6 14-09-2020 11 1   Download

A new theory for ab initio calculation of the anharmonic Extended X-ray Absorption Fine Structure (EXAFS) and its parameters of hcp crystals has been developed based on the single- shell model. Analytical expressions for the anharmonic contributions to the amplitude and to the phase of EXAFS and a new anharmonic factor have been derived. The EXAFS cumulant expressions are formulated based on the anharmonic correlated Einstein model. The EXAFS function and its parameters contain anharmonic effects at high temperature and appoach those of the harmonic model at low temperature.

11p 12120609 01-06-2020 11 1   Download

We have investigated the thermodynamic properties of the cubic zirconia ZrO2 using the statistical moment method in the statistical physics. The free energy, thermal lattice expansion coefficient, specific heats at the constant volume and those at the constant pressure, CV and CP , are derived in closed analytic forms in terms of the power moments of the atomic displacements.

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This paper presents vapor-liquid equilibria of pure fluid fluorine which were predicted by Gibbs Ensemble Monte Carlo (GEMC) simulation techniques using our two new 5-site intermolecular pair potentials ab initio. The ab initio pair potentials were established from coupled-cluster calculations, using the CCSD(T) level of theory and Dunning's correlation consistent basis sets aug-cc-pVmZ (m =2, 3) [8]. The coexistence phase diagram, and the resulting critical properties, thermodynamic properties, vapor pressures and orthobaric densities are found to correspond well with the experimental data.

5p nguathienthan1 20-11-2019 11 0   Download

Michael addition reaction of the 2-amino-1,3,4-thiadiazole to chalcone as biselectrophile afforded 5,7-diphenyl-6-[1,3-diphenylpropan-1-on-3-yl][1,3,4]thiadiazolo[3,2-a]pyrimidine (3) instead of 5,7-diphenyl-5H-[1,3,4]thiadiazolo[3,2-a]pyrimidine (5) via further Michael addition at C5 in pyrimidine moiety. The structure 3 was established through the aspect of ab initio calculations, elemental analysis and spectral data.

5p kethamoi1 17-11-2019 18 1   Download

The effects of charge doping on the strain and electronic structure of ultra-small single-walled carbon nanotubes (SWNTs) are investigated by using first principle calculations. The obtained results show that the actuator strain and Fermi energy of the SWNTs are a function of charge doping level.

5p viminotaur2711 29-10-2019 10 0   Download

The ab initio calculation reveals that a strong repulsive force driven by the solvation potential exceeds the interparticle attraction and predicts the agglomeration energy required for two 10-nm Ti NPs to be 4
1017 J. The collision theory suggests that Ti NPs can be effective suppressors of the SWR due to the high energy barrier that prevents significant agglomeration of Ti NPs in quiescent liquid Na.

7p minhxaminhyeu5 30-06-2019 10 2   Download