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.

Gas Phase Cluster Formation of Sodium Chloride and Water: Monte Carlo Simulations

1991 ◽  
Vol 46 (4) ◽  
pp. 351-356
Author(s):  
Bernd M. Rode
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Cluster Formation ◽  
Ion Pairs ◽  
Particle Interaction ◽  
Distribution Functions ◽  
Prebiotic Atmosphere ◽  
Low Concentrations ◽  
Phase Cluster ◽  
Simulation Parameters

Abstract Monte Carlo simulations of a system of 200 water and 24 NaCl molecules at 6 different densities in the range from 0.003 g/cm3 to 0.999 g,/cm3 and T = 125 °C and 225 CC were performed to obtain some insight into cluster formation which should precede and determine the formation of aerosol structures and has possibly played some role in prebiotic atmosphere chemistry. Solute hydration occurs already at very low concentrations mainly in the form of hydrated molecules ("contact ion pairs"). At higher densities larger cluster structures are observed, leading rather continuously to the structure of the supersaturated 7.1 M NaCl solution at the same temperature. Radial distribution functions, coordination numbers and particle interaction energies are discussed with respect to the simulation parameters density and temperature

scholarly journals Monte Carlo simulations of the electron short-range quantum ordering in Coulomb systems and the “fermionic sign problem”.

2021 ◽  
Author(s):  
Vladimir S Filinov ◽  
Pavel Levashov ◽  
Alexander Larkin
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Path Integral ◽  
Short Range ◽  
Coulomb Systems ◽  
Thermodynamic Characteristics ◽  
Distribution Functions ◽  
Path Integral Monte Carlo ◽  
Path Integral Representation ◽  
Sign Problem

Abstract To account for the interference effects of the Coulomb and exchange interactions of electrons the new path integral representation of the density matrix has been developed in the canonical ensemble at finite temperatures. The developed representation allows to reduce the notorious ``fermionic sign problem'' in the path integral Monte Carlo simulations of fermionic systems. The obtained results for pair distribution functions in plasma and uniform electron gas demonstrate the short--range quantum ordering of electrons associated in literature with exchange--correlation excitons. The charge estimations show the excitonic electric neutrality. Comparison of the internal energy with available ones in the literature demonstrates that the short range ordering does not give noticeable contributions in integral thermodynamic characteristics. This fine physical effect was not observed earlier in the standard path integral Monte Carlo simulations.

scholarly journals Low-frequency Raman Spectroscopy of Aqueous Solutions of Aliphatic Alcohols

2001 ◽  
Vol 56 (8) ◽  
pp. 529-536 ◽  
Author(s):  
Koji Ydoshida ◽  
Toshio Yamaguchi
Keyword(s):  
Aqueous Solutions ◽  
Raman Spectra ◽  
Mole Fraction ◽  
Water Clusters ◽  
Pure Water ◽  
Low Frequency ◽  
Isosbestic Point ◽  
X Ray Diffraction ◽  
Alcohol Water ◽  
Solvent Clusters

Abstract Low-frequency Raman spectra have been measured at room temperature as functions of the alcohol mole fraction in aqueous solutions of methanol, ethanol, 1-propanol, 2 -propanol, and /er/-butylalcohol (TBA). Intrinsic Raman spectra R (ῡ) were obtained from depolarized Rayleigh wing spectra. Isosbestic points have been observed in R (ῡ) of the aqueous solutions of ethanol, 1-propanol, and 2 -propanol, suggesting that the structure o f the solutions is characterized by individual alcohol aggregates and water clusters without a significant amount of alcohol-water mixed aggregates. The R (ῡ) spectra have been expressed as R (ῡ ,x ) = w R (ῡ ,0 ) + aR(D, 1), where R(ῡ, 0) and R(ῡ, 1) are those for pure water and pure alcohols, respectively, and x is the mole fraction of alcohols. The coefficients w and a show the inflection points at characteristic alcohol mole fractions, where microhetrogeneity and structural transition of the solvent clusters take place, as previously shown by X-ray diffraction. In the aqueous solutions of methanol, where no microhetrogeneity takes place, no clear isosbestic point in R(ῡ) has been observed. For aqueous solutions of TBA, an isosbestic point in R(ῡ) has appeared when xTBA > 0.05. Two inflections points in the coefficients have been observed at xTBA « 0.1 and 0.35; the former composition corresponds to the transition composition from the TBA-TBA intermolecular contact to the TBA water molecular association, as previously reported by neutron diffraction.

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