Density functional theory study of the stability of the tetrabutylphosphonium and tetrabutylammonium montmorillonites

Clay Minerals ◽  
2019 ◽  
Vol 54 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Eva Scholtzová ◽  
Daniel Tunega
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Dynamic Properties ◽  
Organic Cations ◽  
Structure Stability ◽  
Functional Theory ◽  
Interatomic Distances ◽  
Principle Density Functional Theory ◽  
The Stability

AbstractThe stability of organoclays prepared from smectites and organic cations depends on the type of used cation, among other factors. This study provides a prediction of the structure, stability and dynamic properties of organoclays based on montmorillonite (Mt) intercalated with two types of organic cations – tetrabutylammonium (TBA) and tetrabutylphosphonium (TBP) – using first-principle density functional theory. The results obtained from simulations were also used in the interpretation of the experimental infrared spectrum of the TBP-Mt organoclay. Analysis of interatomic distances showed that weak C–O···H hydrogen bonds were important in the stabilization of both TBA- and TBP-Mt models, with slightly stronger hydrogen bonds for the TBP cation. Calculated intercalation and adsorption reaction energies (ΔEint//ΔEads*/ΔEads**) confirmed that TBP-Mt structures (–72.4//–32.8/–53.8 kJ/mol) were considerably more stable than TBA-Mt structures (–56.7//–22.6/–37.4 kJ/mol). The stronger interactions of the alkyl chains of the TBP cation with Mt basal surfaces in comparison to those of the TBA cation were also correlated with the positions of the calculated bands of the C–H stretching vibrations.

scholarly journals The stability and electronic and photocatalytic properties of the ZnWO4 (010) surface determined from first-principles and thermodynamic calculations

RSC Advances ◽  
2021 ◽  
Vol 11 (38) ◽  
pp. 23477-23490
Author(s):  
Yonggang Wu ◽  
Jihua Zhang ◽  
Bingwei Long ◽  
Hong Zhang
Keyword(s):  
Phase Diagram ◽  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Thermodynamic Calculations ◽  
Photocatalytic Properties ◽  
Thermodynamic Approach ◽  
Functional Theory ◽  
Stability Phase Diagram ◽  
The Stability

The ZnWO4 (010) surface termination stability is studied using a density functional theory-based thermodynamic approach. The stability phase diagram shows that O-Zn, DL-W, and DL-Zn terminations of ZnWO4 (010) can be stabilized.

scholarly journals Spectroscopic, X-ray Diffraction and Density Functional Theory Study of Intra- and Intermolecular Hydrogen Bonds in Ortho-(4-tolylsulfonamido)benzamides

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 926
Author(s):  
Malose J. Mphahlele ◽  
Eugene E. Onwu ◽  
Marole M. Maluleka
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Tetrahedral Geometry ◽  
Hindered Rotation ◽  
Hydrogen Bond Acceptor ◽  
Functional Theory ◽  
Vis Spectroscopy ◽  
Hydrogen Bonded

The conformations of the title compounds were determined in solution (NMR and UV-Vis spectroscopy) and in the solid state (FT-IR and XRD), complemented with density functional theory (DFT) in the gas phase. The nonequivalence of the amide protons of these compounds due to the hindered rotation of the C(O)–NH2 single bond resulted in two distinct resonances of different chemical shift values in the aromatic region of their 1H-NMR spectra. Intramolecular hydrogen bonding interactions between the carbonyl oxygen and the sulfonamide hydrogen atom were observed in the solution phase and solid state. XRD confirmed the ability of the amide moiety of this class of compounds to function as a hydrogen bond acceptor to form a six-membered hydrogen bonded ring and a donor simultaneously to form intermolecular hydrogen bonded complexes of the type N–H···O=S. The distorted tetrahedral geometry of the sulfur atom resulted in a deviation of the sulfonamide moiety from co-planarity of the anthranilamide scaffold, and this geometry enabled oxygen atoms to form hydrogen bonds in higher dimensions.

scholarly journals Compression Behavior and Vibrational Properties of New Energetic Material LLM-105 Analyzed Using the Dispersion-Corrected Density Functional Theory

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6831
Author(s):  
Tianming Li ◽  
Junyu Fan ◽  
Zhuoran Wang ◽  
Hanhan Qi ◽  
Yan Su ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Uniaxial Compression ◽  
Density Functional ◽  
Structural Parameters ◽  
Energetic Material ◽  
Structure Stability ◽  
Vibrational Properties ◽  
Detailed Knowledge ◽  
Functional Theory

The 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is a newly energetic material with an excellent performance and low sensitivity and has attracted considerable attention. On the basis of the dispersion-corrected density functional theory (DFT-D), the high-pressure responses of vibrational properties, in conjunction with structural properties, are used to understand its intermolecular interactions and anisotropic properties under hydrostatic and uniaxial compressions. At ambient and pressure conditions, the DFT-D scheme could reasonably describe the structural parameters of LLM-105. The hydrogen bond network, resembling a parallelogram shape, links two adjacent molecules and contributes to the structure stability under hydrostatic compression. The anisotropy of LLM-105 is pronounced, especially for Raman spectra under uniaxial compression. Specifically, the red-shifts of modes are obtained for [100] and [010] compressions, which are caused by the pressure-induced enhance of the strength of the hydrogen bonds. Importantly, coupling modes and discontinuous Raman shifts are observed along [010] and [001] compressions, which are related to the intramolecular vibrational redistribution and possible structural transformations under uniaxial compressions. Overall, the detailed knowledge of the high-pressure responses of LLM-105 is established from the atomistic level. Uniaxial compression responses provide useful insights for realistic shock conditions.

6-Bromoindigo dye

2012 ◽  
Vol 68 (4) ◽  
pp. o160-o163 ◽  
Author(s):  
David J. Szalda ◽  
Keith Ramig ◽  
Olga Lavinda ◽  
Zvi C. Koren ◽  
Lou Massa
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Stacking Interactions ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Functional Theory ◽  
Bond Lengths ◽  
Type C

6-Bromoindigo (MBI) [systematic name: 6-bromo-2-(3-oxo-2,3-dihydro-1H-indol-2-ylidene)-2,3-dihydro-1H-indol-3-one], C16H9BrN2O2, crystallizes with one disordered molecule in the asymmetric unit about a pseudo-inversion center, as shown by the Br-atom disorder of 0.682 (3):0.318 (3). The 18 indigo ring atoms occupy two sites which are displaced by 0.34 Å from each other as a result of this packing disorder. This difference in occupancy factors results in each atom in the reported model used to represent the two disordered sites being 0.08 Å from the higher-occupancy site and 0.26 Å from the lower-occupancy site. Thus, as a result of the disorder, the C—Br bond lengths in the disordered components are 0.08 and 0.26 Å shorter than those found in 6,6′-dibromoindigo (DBI) [Süsse & Krampe (1979).Naturwissenschaften,66, 110], although the distances within the indigo ring are similar to those found in DBI. The crystals are also twinned by merohedry. Stacking interactions and hydrogen bonds are similar to those found in the structures of indigo and DBI. In MBI, an interaction of the type C—Br...C replaces the C—Br...Br interactions found in DBI. The interactions in MBI were calculated quantum mechanically using density functional theory and the quantum theory of atoms in molecules.

Predicting the stability of ternary intermetallics with density functional theory and machine learning

2018 ◽  
Vol 148 (24) ◽  
pp. 241728 ◽  
Author(s):  
Jonathan Schmidt ◽  
Liming Chen ◽  
Silvana Botti ◽  
Miguel A. L. Marques
Keyword(s):  
Machine Learning ◽  
Density Functional Theory ◽  
Density Functional ◽  
Functional Theory ◽  
The Stability

Study of dynamic and thermodynamic properties of zinc-blend and wurtzite cadmium sulfide (CdS) using density functional theory

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Teshome Gerbaba Edossa ◽  
Menberu Mengasha Woldemariam
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Density Functional ◽  
Chemical Potential ◽  
Phonon Dispersion ◽  
Dynamic Properties ◽  
Dielectric Constants ◽  
High Symmetry ◽  
Functional Theory ◽  
Zinc Blend

Abstract The dynamic and thermodynamic properties of wurtzite (wz) and zinc-blend (zb) CdS are investigated within the density functional theory using different approximation methods such as LDA, PBE, and DFT+U. Hellmann–Feynman approach is implemented for the relaxation of atomic position for both phases. To guarantee the accuracy of calculation, the convergence test of total energy with respect to energy cutoff and k-point sampling is performed. The dynamic properties such as phonon dispersion, phonon density of state, frequency along with high symmetry points, static and dynamic polarizability, and dielectric constants are calculated. The obtained values are compared with previous theoretical results. DFT + U approximation gives a good result that is consistent with the available theory. Moreover, the vibrational energy, vibrational free energy, entropy, electron chemical potential, and constant-volume specific heat are obtained within LDA, PBE, and DFT + U approximations.

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