Badanie właściwości termodynamicznych i strukturalnych cieczy polarnych i roztworów elektrolitów metodą Monte Carlo
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2012-06-06T12:40:45Z
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Investigation of structural and thermodynamic properties of polar solvents and electrolyte solutions by the Monte Carlo method
Abstract
Badano właściwości termodynamiczne oraz strukturalne cieczy polarnych oraz roztworów elektrolitu metodami symulacji MC. Dla modelu DHS (Dipolar Hard Sphere) oraz nieprymitywnego modelu elektrolitu w zespole kanonicznym obliczono energię wewnętrzną, pojemność cieplną oraz względną przenikalność elektryczną ośrodka, a także określono funkcje radialne i orientacyjne. Szczególny nacisk położono na obliczenie współczynników aktywności metodą IGCMC dla różnych modeli cieczy polarnych oraz dla nieprymitywnego modelu elektrolitu. Wyniki uzyskane z symulacji porównano z obliczonymi na podstawie teorii MSA (Mean Spherical Approximation) oraz PT (Perturbation Theory). W przypadku modelu DHS przebadano wpływ gęstości zredukowanej, momentu dipolowego, średnicy, oraz temperatury na wartości współczynnika aktywności. Najlepszą zgodność wyników symulacyjnych z teoretycznymi uzyskano dla PT. Dla bardziej złożonych modeli cieczy polarnych tj. dipolowego Yukawy i Stockmayera analizowano wpływ gęstości zredukowanej oraz zredukowanego momentu dipolowego na wartość współczynnika aktywności. Wyniki porównano z uzyskanymi z MSA, PT oraz z teorii Kronome-Liszi-Szalai. W przypadku nieprymitywnego modelu elektrolitu analizowano wpływ stężenia, zredukowanego momentu dipolowego oraz średnicy cząsteczek rozpuszczalnika na wartość współczynnika aktywności. Pokazano, że MSA daje lepsze wartości współczynników aktywności niż PT.
The subject of investigations was the structural and thermodynamic properties of different models of a polar fluid and nonprimitive model of an electrolyte. The investigations were carried out by the Monte Carlo simulations techniques in the canonical and grand canonical ensemble. The internal energy u, heat capacity Cv and the relative eclectic permittivity εr were calculated. The PT theory gives the best agreement between the internal energy results with those of the simulations at low reduced densities ρ* and low reduced dipole moments μ*. The influence of the density number, electric dipole moment, diameter of a hard sphere, and temperature on the activity coefficient predicted by the DHS model was analyzed. The activity coefficient of the dipolar Yukawa and Stockmayer model were calculated from the IGCMC method. A comparison of the results obtained assuming the PT, MSA and theory given by Kronome Liszi and Szalai results is presented. The internal energy, heat capacity and the relative electric permittivity for the nonprimitive model of electrolyte were calculated by MC simulation. The internal energy increased with c and μ. The best agreements between MC results were obtained with those predicted by PT theo. The mean activity coefficient for nonprimitive electrolyte model was calculated by IGCMC. Two cases were considered. In the first, the diameters of ions and dipoles were the same, while in the second diameters of solvent the were different. In both cases the influence of electrolyte concentration c was analyzed. The best agreement between MC the theoretical results was observed for the MSA theory.
The subject of investigations was the structural and thermodynamic properties of different models of a polar fluid and nonprimitive model of an electrolyte. The investigations were carried out by the Monte Carlo simulations techniques in the canonical and grand canonical ensemble. The internal energy u, heat capacity Cv and the relative eclectic permittivity εr were calculated. The PT theory gives the best agreement between the internal energy results with those of the simulations at low reduced densities ρ* and low reduced dipole moments μ*. The influence of the density number, electric dipole moment, diameter of a hard sphere, and temperature on the activity coefficient predicted by the DHS model was analyzed. The activity coefficient of the dipolar Yukawa and Stockmayer model were calculated from the IGCMC method. A comparison of the results obtained assuming the PT, MSA and theory given by Kronome Liszi and Szalai results is presented. The internal energy, heat capacity and the relative electric permittivity for the nonprimitive model of electrolyte were calculated by MC simulation. The internal energy increased with c and μ. The best agreements between MC results were obtained with those predicted by PT theo. The mean activity coefficient for nonprimitive electrolyte model was calculated by IGCMC. Two cases were considered. In the first, the diameters of ions and dipoles were the same, while in the second diameters of solvent the were different. In both cases the influence of electrolyte concentration c was analyzed. The best agreement between MC the theoretical results was observed for the MSA theory.
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Wydział Chemii: Instytut Chemii fizycznej
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współczynnik aktywności, activity coefficient, Monte Carlo, Monte Carlo, ciecze polarne, polar fluids, elektrolity, electrolytes