scholarly journals MONTE CARLO SIMULATIONS OF Co (II) IN WATER INCLUDING THREE-BODY CORRECTION

2010 ◽  
Vol 6 (3) ◽  
pp. 280-285
Author(s):  
Cahyorini Kusumawardani ◽  
Harno Dwi Pranowo ◽  
Crys Fajar Partana ◽  
Mudasir Mudasir
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Coordination Number ◽  
Pair Interaction ◽  
Angular Distributions ◽  
Radial Density ◽  
Pair Potentials ◽  
Interaction Terms ◽  
Energy And Angular Distributions ◽  
Three Body

In order to describe the cobalt-water interaction correctly, a new ab initio potential was developed consisting of pair interaction terms as well as three-body contributions. Within this approach, it was possible to correct for the well-known failures of pair potentials in describing solvation phenomena of such ions. A first-shell coordination number of 6 in agreement with experimental data were obtained from Monte Carlo simulations of a single cobalt (II) ion in water. The structure of hydrated ion is discussed in terms of radial density functions and coordination number, energy and angular distributions.   Keywords: MC Simulations, cobalt(II), hydration, three-body correction

Triple-Defect B2 Binary Intermetallics: Bragg-Williams Solution and Monte Carlo Simulations

2009 ◽  
Vol 289-292 ◽  
pp. 361-368 ◽  
Author(s):  
Andrzej Biborski ◽  
L. Zosiak ◽  
Rafal Abdank-Kozubski
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Vacancy Concentration ◽  
A Priori ◽  
Equilibrium Concentration ◽  
Pair Interaction ◽  
Type Model ◽  
Interaction Energies ◽  
Atomic Pair ◽  
Antisite Defects

Surprisingly low rate of “order-order” kinetics in stoichiometric NiAl intermetallic known of very high vacancy concentration suggested a specific triple-defect mechanism of ordering/disordering in this system [1]. This mechanism implies a correlation between the concentrations of antisite defects and vacancies; the latters being trapped in triple defects and thus, inactive as atomic migration agents. The process was modelled by means of Monte Carlo (MC) simulations recognised as a powerful tool for such tasks [2], but requiring now the implementation of thermal vacancy thermodynamics. Temperature dependence of vacancy concentration in an AB B2 binary system was determined within an Ising-type model solved first in Bragg-Williams approximation [3] and then by means of MC simulation of a Grandcanonical Ensemble. Without any a priori assumptions concerning the formation of particular types of point defects the model yielded temperature domains where the concentrations of antisite defects and vacancies were proportional. The effect associated with the formation of triple defects appeared for specific values of atomic pair-interaction energies. Moreover, non-stoichiometric A-B systems with the same atomic pair-interaction energies showed the existence of constitutional vacancies at low temperatures. Monte Carlo simulations of “order-order” (disordering) kinetics in B2 AB systems modelled with triple-defect-promoting atomic pair-interaction energies were run with temperature-dependent concentra-tion (i.e. number) of vacancies given by the above model. The simulated relaxations showed two stages: (i) rapid formation of triple defects engaging almost all vacancies present in the system, (ii) very slow process of further generation of antisite defects until the equilibrium concentration was reached. The result reproduced very well the experimental observations [1].

Interionic Potentials and MC Simulations of Molten AgCl

1988 ◽  
Vol 43 (8-9) ◽  
pp. 751-754 ◽  
Author(s):  
C. Margheritis ◽  
C. Sinistri
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Solid Phase ◽  
Energy Effect ◽  
Polarization Energy ◽  
Pair Potentials

Abstract Monte Carlo simulations on molten AgCl were carried out in order to test the applicability of the interionic potentials recently proposed for this salt in the solid phase. None of the literature potentials can be used as such: in all cases pairs of like ions reach too short distances of approach causing the collapse of the system. It was proved that, in order to obtain equilibration of the system, the pair potentials of like ions must be recalculated.On the basis of these modified potentials, MC simulations of molten AgCl were carried out at 728 (m.p.), 1000 and 1500 K. The polarization energy effect was also analyzed with the use of a soft ion model.

Monte Carlo Simulations of Zn(II) in Water Including Three-Body Effects

1996 ◽  
Vol 100 (16) ◽  
pp. 6808-6813 ◽  
Author(s):  
Gerhard W. Marini ◽  
Norbert R. Texler ◽  
Bernd M. Rode
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Three Body

scholarly journals Photodissociation of Iso-Propoxy (I-C3H7O) Radical at 248 Nm

2020 ◽  
Author(s):  
Erin Sullivan ◽  
Steven Saric ◽  
Daniel Neumark
Keyword(s):  
Electronic State ◽  
Ground State ◽  
Branching Ratio ◽  
Ground Electronic State ◽  
Angular Distributions ◽  
Translational Energy ◽  
Energy And Angular Distributions ◽  
Three Body ◽  
State Dissociation

<p>Photodissociation of the <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radical is investigated using fast beam photofragment translational spectroscopy. Neutral <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radicals are produced through the photodetachment of a fast beam of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O<sup>-</sup> anions and are subsequently dissociated using 248 nm (5.0 eV). The dominant product channels are CH<sub>3</sub> + CH<sub>3</sub>CHO and OH + C<sub>3</sub>H<sub>6</sub> with some contribution from H + C<sub>3</sub>H<sub>6</sub>O. CH<sub>3</sub> and H loss are attributed to dissociation on the ground electronic state of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O, but in a nonstatistical manner because RRKM dissociation rates exceed the rate of energy randomization. Translational energy and angular distributions for OH loss are consistent with ground state dissociation, but the branching ratio for this channel is considerably higher than predicted from RRKM rate calculations. These results corroborate what has been observed previously in C<sub>2</sub>H<sub>5</sub>O dissociation at 5.2 eV that yields CH<sub>3</sub>, H, and OH loss. Additionally, <i>i</i>-C<sub>3</sub>H<sub>7</sub>O undergoes three-body fragmentation to CH<sub>3</sub> + CH<sub>3</sub> + HCO and CH<sub>3</sub> + CH<sub>4</sub> + CO. These three-body channels are attributed to dissociation of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O to CH<sub>3</sub> + CH<sub>3</sub>CHO, followed by secondary dissociation of CH<sub>3</sub>CHO on its ground electronic state.</p>

scholarly journals Photodissociation of Iso-Propoxy (I-C3H7O) Radical at 248 Nm

2020 ◽  
Author(s):  
Erin Sullivan ◽  
Steven Saric ◽  
Daniel Neumark
Keyword(s):  
Electronic State ◽  
Ground State ◽  
Branching Ratio ◽  
Ground Electronic State ◽  
Angular Distributions ◽  
Translational Energy ◽  
Energy And Angular Distributions ◽  
Three Body ◽  
State Dissociation

<p>Photodissociation of the <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radical is investigated using fast beam photofragment translational spectroscopy. Neutral <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radicals are produced through the photodetachment of a fast beam of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O<sup>-</sup> anions and are subsequently dissociated using 248 nm (5.0 eV). The dominant product channels are CH<sub>3</sub> + CH<sub>3</sub>CHO and OH + C<sub>3</sub>H<sub>6</sub> with some contribution from H + C<sub>3</sub>H<sub>6</sub>O. CH<sub>3</sub> and H loss are attributed to dissociation on the ground electronic state of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O, but in a nonstatistical manner because RRKM dissociation rates exceed the rate of energy randomization. Translational energy and angular distributions for OH loss are consistent with ground state dissociation, but the branching ratio for this channel is considerably higher than predicted from RRKM rate calculations. These results corroborate what has been observed previously in C<sub>2</sub>H<sub>5</sub>O dissociation at 5.2 eV that yields CH<sub>3</sub>, H, and OH loss. Additionally, <i>i</i>-C<sub>3</sub>H<sub>7</sub>O undergoes three-body fragmentation to CH<sub>3</sub> + CH<sub>3</sub> + HCO and CH<sub>3</sub> + CH<sub>4</sub> + CO. These three-body channels are attributed to dissociation of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O to CH<sub>3</sub> + CH<sub>3</sub>CHO, followed by secondary dissociation of CH<sub>3</sub>CHO on its ground electronic state.</p>

The Structure of Hydroxylamine – Water Mixtures

1995 ◽  
Vol 50 (2-3) ◽  
pp. 263-273 ◽  
Author(s):  
Sergi Vizoso ◽  
Bernd M. Rode
Keyword(s):  
Monte Carlo ◽  
Hydrogen Bonding ◽  
Angular Distribution ◽  
Aqueous Solutions ◽  
Monte Carlo Simulations ◽  
Coordination Number ◽  
Water Clusters ◽  
Pure Water ◽  
Distribution Functions ◽  
Pair Energy

Abstract Monte Carlo simulations have been carried our for 5, 25, 50, and 75 weight% aqueous solutions of hydroxylamine. Changes in the microstructure of the solutions have been evaluated by means of radial and angular distribution functions, coordination number distributions and pair energy anal­ysis. The structure of liquid hydroxylamine is strongly altered by even small amounts of water, whereas water clusters similar to the pure water are maintained up to higher NH2OH concentra­tions. The structural entities in the mixtures are determined by hydrogen bonding and electrostatic arrangement of ligands.

Three-dimensional Monte Carlo simulations of materials on the physical deposition process

2017 ◽  
Vol 31 (24) ◽  
pp. 1750165
Author(s):  
Abbas Drize ◽  
Abderrahmane Settaouti
Keyword(s):  
Monte Carlo ◽  
Hard Spheres ◽  
Three Dimensional ◽  
Deposition Process ◽  
Thin Layers ◽  
Angular Distributions ◽  
And Topology ◽  
Physical Deposition ◽  
Target Pressure ◽  
Energy And Angular Distributions

The sputtering technique is largely used for the deposition of thin layers. In this study, the Monte Carlo (MC) method combined with the binary collision theory of hard spheres is used to simulate the energy, direction and topology of the film deposit. The effects of several parameters such as the substrate, target, pressure and the distance between substrate and target were analyzed. Our results showed that for large pressures or distances, energy and angular distributions are uniform and consequently the obtained film will be uniform. The obtained results are in agreement with other works, which validates our calculations.

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