The Rattling and Rotation Behaviours of the Hydrated Excess Proton in Water

10.26434/chemrxiv.8179274 ◽

2019 ◽

Author(s):

Shuping Bi

Keyword(s):

Density Functional ◽

Room Temperature ◽

Zero Point ◽

Water Molecules ◽

Rotational Behaviour ◽

Functional Theory ◽

Solvent Water ◽

Grotthuss Mechanism ◽

The Density Functional Theory ◽

Migration Mechanism

The rattling and rotation behaviours of the hydrated excess proton (H+) in water are investigated using the density functional theory–quantum chemical cluster model (DFT-CM) method. The rattling pathways for the target proton *H+ between two adjacent O atoms in the form of Zundel configurations with symmetrical solvation environments are obtained. The zero-point contribution reduces the reaction energy barrier and enables the rattling to occur spontaneously at room temperature. The rotational behaviour of *H+ in the form of *H+·H2O* is found. Upon *H+·H2O* rotation, *H+ changes its position accompanied by concerted displacement of surrounding solvent water molecules and the breaking and formation of hydrogen bonds. The “*H+·H2O* rotating migration mechanism” is proposed for the proton transfer mechanism in water — the same *H+ migrates via *H+·H2O* rotation through void in solvent water, rather than different protons hopping along water hydrogen bond chains as known as the Grotthuss mechanism.

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Computational Evidence Suggests That 1-chloroethanol May Be an Intermediate in the Thermal Decomposition of 2-chloroethanol into Acetaldehyde and HCl

10.26434/chemrxiv.7608857.v1 ◽

2019 ◽

Author(s):

Zoi Salta ◽

Agnie M. Kosmas ◽

Oscar Ventura ◽

Vincenzo Barone

Keyword(s):

Aqueous Solution ◽

Water Molecule ◽

Gas Phase ◽

Density Functional ◽

Water Molecules ◽

Functional Theory ◽

Direct Transformation ◽

The Density Functional Theory ◽

Successive Step ◽

The One

The dehalogenation of 2-chloroethanol (2ClEtOH) in gas phase with and without participation of catalytic water molecules has been investigated using methods rooted into the density functional theory. The well-known HCl elimination leading to vinyl alcohol (VA) was compared to the alternative elimination route towards oxirane and shown to be kinetically and thermodynamically more favorable. However, the isomerization of VA to acetaldehyde in the gas phase, in the absence of water, was shown to be kinetically and thermodynamically less favorable than the recombination of VA and HCl to form the isomeric 1-chloroethanol (1ClEtOH) species. This species is more stable than 2ClEtOH by about 6 kcal mol-1, and the reaction barrier is 22 kcal mol-1 vs 55 kcal mol-1 for the direct transformation of VA to acetaldehyde. In a successive step, 1ClEtOH can decompose directly to acetaldehyde and HCl with a lower barrier (29 kcal mol-1) than that of VA to the same products (55 kcal mol-1). The calculations were repeated using a single ancillary water molecule (W) in the complexes 2ClEtOH_W and 1ClEtOH_W. The latter adduct is now more stable than 2ClEtOH_W by about 8 kcal mol-1, implying that the water molecule increased the already higher stability of 1ClEtOH in the gas phase. However, this catalytic water molecule lowers dramatically the barrier for the interconversion of VA to acetaldehyde (from 55 to 6 kcal mol-1). This barrier is now smaller than the one for the conversion to 1ClEtOH (which also decreases, but not so much, from 22 to 12 kcal mol-1). Thus, it is concluded that while 1ClEtOH may be a plausible intermediate in the gas phase dehalogenation of 2ClEtOH, it is unlikely that it plays a major role in water complexes (or, by inference, aqueous solution). It is also shown that neither in the gas phase nor in the cluster with one water molecule, the oxirane path is competitive with the VA alcohol path.

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Electronic Structure and Magnetic Properties of Ti-doped ZnO

MRS Proceedings ◽

10.1557/proc-1183-ff10-14 ◽

2009 ◽

Vol 1183 ◽

Cited By ~ 1

Author(s):

Soumia Lardjane ◽

Ghouti Merad ◽

Houda Imane Faraoun

Keyword(s):

Density Functional ◽

Room Temperature ◽

Magnetic Semiconductor ◽

Magnetic Element ◽

Functional Theory ◽

Magnetic Structures ◽

Spintronic Devices ◽

The Density Functional Theory ◽

Doped Zno ◽

Ferromagnetic Ordering

AbstractRecent experiments suggest that Ti doped ZnO can be a promising room temperature dilute magnetic semiconductor (DMS) and a potentially useful material for spintronic devices. Furthermore, the fact that Ti doped ZnO shows ferromagnetic behaviour despite it contains no magnetic element makes this system good candidate for theoretical investigation regarding the controversies about the origin of ferromagnetic ordering in TM-doped ZnO. In this work, the density functional theory (DFT) is used to calculate the electronic and magnetic structures of Ti-doped ZnO. The obtained results are used to discuss the origin of the ferromagnetism, and the contribution of different atoms in the magnetic moment.

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A combined study of the equation of state of monazite-type lanthanum orthovanadate usingin situhigh-pressure diffraction andab initiocalculations

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520614010816 ◽

2014 ◽

Vol 70 (3) ◽

pp. 533-538 ◽

Cited By ~ 10

Author(s):

Olga Ermakova ◽

Javier López-Solano ◽

Roman Minikayev ◽

Stefan Carlson ◽

Agata Kamińska ◽

...

Keyword(s):

Equation Of State ◽

Density Functional ◽

Room Temperature ◽

Theoretical Data ◽

Perfect Agreement ◽

Functional Theory ◽

Compression Direction ◽

The Density Functional Theory ◽

Murnaghan Equation

Lanthanum orthovanadate (LaVO4) is the only stable monazite-type rare-earth orthovanadate. In the present paper the equation of state of LaVO4is studied usingin situhigh-pressure powder diffraction at room temperature, andab initiocalculations within the framework of the density functional theory. The parameters of a second-order Birch–Murnaghan equation of state,i.e.those fitted to the experimental and theoretical data, are found to be in perfect agreement – in particular, the bulk moduli are almost identical, with values of 106 (1) and 105.8 (5) GPa, respectively. In agreement with recent reported experimental data, the compression is shown to be anisotropic. Its nature is comparable to that of some other monazite-type compounds. The softest compression direction is determined.

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Investigation of the absorption of CO2 in ionic liquid

Bangladesh Journal of Scientific Research ◽

10.3329/bjsr.v29i1.29756 ◽

2016 ◽

Vol 29 (1) ◽

pp. 41-46

Author(s):

Kalyan Dhar ◽

Syed Fahim

Keyword(s):

Ionic Liquid ◽

Binding Sites ◽

Density Functional ◽

Room Temperature ◽

Minimum Energy ◽

Environmental Concerns ◽

Co2 Absorption ◽

Solvation Model ◽

Functional Theory ◽

The Density Functional Theory

Due to environmental concerns, current interest is the development of technologies that may be able to remove CO2 efficiently from exhaust gases and thus avoid its dispersion in the atmosphere. The density functional theory (DFT) calculations with the modern continuum solvation model (IEFPCM-SMD) was used to study the mechanism of CO2 absorption in room temperature ionic liquid such as, [EMIM][BF4] (1-ethyl-3- methylimidazolium tetrafluoroborate). We determine the minimum energy structures and to determine the possible binding sites for CO2 absorption process in [EMIM][BF4]; by comparing the relative minimum energy of [EMIM][BF4] in the presence and absence of CO2.Bangladesh J. Sci. Res. 29(1): 41-46, June-2016

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Thermoelectric characteristics of X$$_2$$YH$$_2$$ monolayers (X=Si, Ge; Y=P, As, Sb, Bi): a first-principles study

Scientific Reports ◽

10.1038/s41598-021-03280-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mohammad Ali Mohebpour ◽

Shobair Mohammadi Mozvashi ◽

Sahar Izadi Vishkayi ◽

Meysam Bagheri Tagani

Keyword(s):

Thermoelectric Materials ◽

First Principles ◽

Material Science ◽

Figure Of Merit ◽

Density Functional ◽

Room Temperature ◽

Boltzmann Transport Equation ◽

Boltzmann Transport ◽

Functional Theory ◽

The Density Functional Theory

AbstractEver since global warming emerged as a serious issue, the development of promising thermoelectric materials has been one of the main hot topics of material science. In this work, we provide an in-depth understanding of the thermoelectric properties of X$$_2$$ 2 YH$$_2$$ 2 monolayers (X=Si, Ge; Y=P, As, Sb, Bi) using the density functional theory combined with the Boltzmann transport equation. The results indicate that the monolayers have very low lattice thermal conductivities in the range of 0.09−0.27 Wm$$^{-1}$$ - 1 K$$^{-1}$$ - 1 at room temperature, which are correlated with the atomic masses of primitive cells. Ge$$_2$$ 2 PH$$_2$$ 2 and Si$$_2$$ 2 SbH$$_2$$ 2 possess the highest mobilities for hole (1894 cm$$^2$$ 2 V$$^{-1}$$ - 1 s$$^{-1}$$ - 1 ) and electron (1629 cm$$^2$$ 2 V$$^{-1}$$ - 1 s$$^{-1}$$ - 1 ), respectively. Si$$_2$$ 2 BiH$$_2$$ 2 shows the largest room-temperature figure of merit, $$ZT=2.85$$ Z T = 2.85 in the n-type doping ( $$\sim 3\times 10^{12}$$ ∼ 3 × 10 12 cm$$^{-2}$$ - 2 ), which is predicted to reach 3.49 at 800 K. Additionally, Si$$_2$$ 2 SbH$$_2$$ 2 and Si$$_2$$ 2 AsH$$_2$$ 2 are found to have considerable ZT values above 2 at room temperature. Our findings suggest that the mentioned monolayers are more efficient than the traditional thermoelectric materials such as Bi$$_2$$ 2 Te$$_3$$ 3 and stimulate experimental efforts for novel syntheses and applications.

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Phase Stability in U-6Nb Alloy Doped with Ti from the First Principles Theory

Applied Sciences ◽

10.3390/app10103417 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3417

Author(s):

Alexander Landa ◽

Per Söderlind ◽

Amanda Wu

Keyword(s):

Phase Stability ◽

First Principles ◽

Density Functional ◽

Room Temperature ◽

Rapid Quenching ◽

Quantum Mechanical ◽

First Principles Calculations ◽

Functional Theory ◽

The Density Functional Theory ◽

Effect Of Impurities

First-principles calculations within the density-functional-theory (DFT) approach are conducted in order to explore and explain the effect of small amounts of titanium on phase stability in the U-6Nb alloy. During rapid quenching from high to room temperature, metastable phases α′ (orthorhombic), α″ (monoclinic), and γ0 (tetragonal) can form, depending on Nb concentration. Important mechanical properties depend on the crystal structure and, therefore, an understanding of the effect of impurities on phase stability is essential. Insights on this issue are obtained from quantum-mechanical DFT calculations. The DFT framework does not rely on any material-specific assumptions and is therefore ideal for an unbiased investigation of the U-Nb system.

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FERROMAGNETIC PROPERTIES IN V-DOPED AlN FROM FIRST PRINCIPLES

Modern Physics Letters B ◽

10.1142/s0217984912501321 ◽

2012 ◽

Vol 26 (20) ◽

pp. 1250132

Author(s):

G. Y. YAO ◽

G. H. FAN ◽

J. H. MA ◽

S. W. ZHENG ◽

J. CHEN ◽

...

Keyword(s):

First Principles ◽

Density Functional ◽

Room Temperature ◽

Magnetic Semiconductor ◽

Double Exchange ◽

Functional Theory ◽

Zinc Blende ◽

The Density Functional Theory ◽

Spin Polarized ◽

Ferromagnetic Ground State

Using the first-principles method based on the density functional theory, we have calculated electronic structure of zinc blende AlN doped with 6.25% of V. The V dopants are found spin polarized and the calculated band structures suggest a 100% polarization of the conduction carriers. The ferromagnetic ground state in V-doped AlN can be explained in terms of double-exchange mechanism, and a Curie temperature above room temperature can be expected. These results suggest that the V-doped AlN may present a promising dilute magnetic semiconductor and find applications in the field of spintronics.

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Formation of intramolecular dimer radical ions of diphenyl sulfones

Scientific Reports ◽

10.1038/s41598-020-76907-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Kazumasa Okamoto ◽

Shunpei Kawai ◽

Takahiro Kozawa

Keyword(s):

Density Functional ◽

Room Temperature ◽

Radical Cations ◽

Excess Charge ◽

Radical Ions ◽

Functional Theory ◽

Aromatic Molecules ◽

Diphenyl Sulfone ◽

The Density Functional Theory ◽

Phenyl Rings

AbstractDimer radical ions of aromatic molecules in which excess charge is localized in a pair of rings have been extensively investigated. While dimer radical cations of aromatics have been previously produced in the condensed phase, the number of molecules that form dimer anions is very limited. In this study, we report the formation of intramolecular dimer radical ions (cations and anions) of diphenyl sulfone derivatives (DPs) by electron beam pulse radiolysis in the liquid phase at room temperature. The density functional theory (DFT) calculations also showed the formation of the dimer radical ions. The torsion barrier of the phenyl ring of DPs was also calculated. It was found that the dimer radical ions show the larger barrier than the neutral state. Finally, stability of the dimer radical anion is dependent on not only the inductive effect of the sulfonyl group but the conjugation involving the d-orbital of the S atom and the phenyl rings.

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Термодинамическая стабильность твердых растворов In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N

Письма в журнал технической физики ◽

10.21883/pjtf.2021.19.51516.18879 ◽

2021 ◽

Vol 47 (19) ◽

pp. 51

Author(s):

С.А. Кукушкин ◽

А.В. Осипов

Keyword(s):

Density Functional ◽

Room Temperature ◽

Epitaxial Films ◽

Hexagonal Structure ◽

Symmetry Groups ◽

Functional Theory ◽

Thermodynamic Potentials ◽

The Density Functional Theory ◽

The Stability ◽

Group Theoretical Analysis

A group-theoretical analysis of solid solutions of indium and gallium nitrides InxGa1-xN was carried out, and all the main symmetry groups were found for these solutions with the initial hexagonal structure. The thermodynamic potentials of the main phases with different compositions x are calculated using the density functional theory. It is shown that for small and large x, i.e. at 0 <x <0.2 and 0.8 <x <1, there is a large number of monoclinic phases Pm and P2_1, which are stable with respect to decomposition into InN and GaN at room temperature. In the range 0.2 <x <0.8, there are only two stable orthorhombic phases Cmc2_1 with compositions x = 1/3 and x = 2/3. All basic geometric and thermodynamic properties of various InxGa1-xN phases have been calculated. It was found that the stability of InxGa1-xN epitaxial films increases with growth on InN and decreases with growth on GaN.

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