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1991 (173)
1Author    M.R P Yukhnovskii, I. V. Kozlovskii, PylyukRequires cookie*
 Title      
 Abstract    A method for the calculation of the thermodynamic functions in the three-dimensional Ising model near the phase transition is proposed. In the frame of a uniform approach, the critical exponents and the critical amplitudes of the main characteristics of the model (i.e. free energy, enthropy, specific heat, etc.) are obtained as functions of microscopic Hamiltonian parameters. It is shown that the correct sign and temperature behaviour of the entropy are provided due to the contribution of the long-wave spin moment modes. The short-wave ones are responsible for the values of the critical exponents. 
  Reference    Z. Naturforsch. 46a, 1—7 (1991); received August 4 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0001.pdf 
 Identifier    ZNA-1991-46a-0001 
 Volume    46 
2Author    O. A. Pizio, Z. B. HalytchRequires cookie*
 Title      
 Abstract    An ion-dipole model of electrolyte solutions in the bulk case and near a charged or uncharged hard wall is considered. A method to derive the terms of optimized cluster expansions for the distribution functions of ions and dipoles which provides a set of approximations beyond the mean spherical approximation is given. The third cluster coefficient approximation is investigated. S t r u c t u r a l P r o p e r tie s o f th e Io n -D ip o le M o d e l o f E le c tr o ly te S o lu tio n s in th e B u lk a n d N e a r a C h a r g e d H a r d W a ll. A p p lic a tio n o f th e T r u n c a te d O p tim iz e d C lu s te r S e rie s 
  Reference    Z. Naturforsch. 46a, 8—18 (1991); received 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0008.pdf 
 Identifier    ZNA-1991-46a-0008 
 Volume    46 
3Author    M. F. Golovko, L. A. ProtsykevychRequires cookie*
 Title     
 Abstract    o lu tio n s o f S o d iu m in L iq u id A m m o n ia a s D e s c rib e d b y a H a r d S p h e re C h a r g e -D ip o le M o d e l in th e N e u tra liz in g B a c k g r o u n d The analytic solution of the mean spherical approximation obtained by us previously for the ion-dipole system in a neutralizing background is applied to study the structural, thermodynamic and dielectric properties of sodium-ammonia solutions. It is shown that the structure of ammonia is closepacked and changes little with ion concentration. The shape of the ion-ion distribution function changes from solvation behaviour with Debye-like asymptotics at low ion concentration to density ordering in the metalic region. 
  Reference    Z. Naturforsch. 46a, 19—26 (1991); received October 23 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0019.pdf 
 Identifier    ZNA-1991-46a-0019 
 Volume    46 
4Author    Baranyai, DenisJ. EvansRequires cookie*
 Title    Andräs  
 Abstract    The expansion of the entropy into one-body, two-body, three-body, etc. contributions was applied to estimate the excess entropy of the hard sphere fluid. Configuration samples provided by computer simulation were used to determine the two-particle and three-particle correlation functions. The results show that even at intermediate densities a non-negligible part of the structural information is represented by four-body and higher order correlations. O n th e E n tr o p y o f th e H a r d S p h e re F lu id 
  Reference    Z. Naturforsch. 46a, 27—31 (1991); received April 11 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0027.pdf 
 Identifier    ZNA-1991-46a-0027 
 Volume    46 
5Author    MichopoulosPeter Botschwina2, BerndM. Rode1Requires cookie*
 Title    Yanos  
 Abstract    Dedicated to Dr. K. Heinzinger on the occasion of his 60 th birthday The derivation of an intermolecular potential function for the interaction of two hydroxylamine molecules, based on ab initio SCF-ECP calculations is reported. Ab initio values were compared for selected geometries with those obtained from calculations with much larger basis sets, inluding electron correlation effects by the CEPA method. A total 658 energy values were then fitted to an analytic sum of atom-atom isotropic pair potential functions, whose functional form was given a simple electrostatic interpretation. The major difficulties, arising from the relatively low values of the stabilisation energies of the system and the numerous possibilities to form hydrogen bonds, were overcome by a careful selection of sufficient points on the potential hypersurface, introduction of cut-offs and weight factors. The obtained function was seen to be able to give a good reproduction of the interaction energies and proved suitable in a preliminary MC simulation. I n te r m o le c u la r P o te n tia l F u n c tio n fo r H y d r o x y la m in e D im e r I n te r a c tio n s fro m a b in itio C a lc u la tio n s 
  Reference    Z. Naturforsch. 46a, 32—38 (1991); received June 29 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0032.pdf 
 Identifier    ZNA-1991-46a-0032 
 Volume    46 
6Author    Slanina, AndreyG. Kalinichev2Requires cookie*
 Title    Zdenek  
 Abstract    Dedicated to Dr. Karl Heinzinger on the occasion of his 60 th birthday. (HDO)2 can form two isomeric species, HOD.OHD and DOH.OHD. The species are studied in terms of the Bopp-Jancsö-Heinzinger potential. The deuterium-bonded structure is stabilized in zero-point vibrational energy by about 0.77 kJ moP1 over the hydrogen-bonded one. In gas-phase the exactly equal stability of both structures would however be reached at a temperature of 638 K. The thermodynamic functions of HOD.OHD and DOH.OHD are different and, moreover, they essentially differ from the (overall) functions belonging to the equilibrium mixture of both structures (which is understood as one pseudospecies). For the heat capacity at constant pressure it is shown that a maximum of the difference between the pseudospecies' overall value and the HOD.OHD value appears at a temperature of about 39 K, amounting to some 4.6 J K-1mol_1. A C o n f ig u ra tio n a l C o n tr ib u tio n to th e H e a t C a p a c ity o f G a s e o u s (H D O) 2 
  Reference    Z. Naturforsch. 46a, 39—42 (1991); received July 18 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0039 
 Volume    46 
7Author    W.A P Luck, S. PeilRequires cookie*
 Title      
 Abstract    Dedicated to Dr. Karl Heinzinger on the occasion of his 60th birthday With the low temperature matrix techique we have observed different isolated IR OH vibration bands caused by van der Waals forces of single atom groups of the matrix molecules. With a series of different perhalogenated matrix molecules these different OH band frequency shifts AvO H can be correlated to OH interactions with C-F, C-Cl, C-Br resp. C-I groups. At higher temperatures T (solution spectra) the band positions of the different interactions become more similar because dv/d T increases with increasing interaction. This result clarifies why at room temperature band shoulders are observed and correlates these clearly to the different matrix bands and therefore to different interactions. These experiments demonstrate that intermolecular van der Waals potentials of asym­ metric molecules cannot be approximated by one spheric potential but are angle dependent. This indicates the complexity of describe condensed media. S p e c tr o s c o p ic I n v e s tig a tio n s o f I n te r m o le c u la r I n te r a c tio n s b e tw e e n D if fe r e n t P a r t s o f M o le c u le s * 
  Reference    Z. Naturforsch. 46a, 43—48 (1991); received August 29 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0043.pdf 
 Identifier    ZNA-1991-46a-0043 
 Volume    46 
8Author    Katalin Tóth, Gabor JancsóRequires cookie*
 Title      
 Abstract    g V ib r a tio n s o f C h lo ro fo rm a n d F lu o ro f o r m The change in the frequency of the CH stretching vibration and in its anharmonicity constant, quadratic, cubic and quartic force constants and the equilibrium CH bond distance, on conden­ sation, were investigated by performing model calculations for liquid chloroform and fluoroform. The interactions between the hydrogen atom and the CH oscillator, represented by a Morse potential, and the halogen atoms of its neighbor molecules were described by the sum of Lennard-Jones and Coulomb potential functions employed in molecular dynamics simulation. The calcula­ tions were carried out for different molecular arrangements in the liquid and have shown that mainly the size of the halogen atom, consequently the intermolecular distances, govern the direction of the CH vibrational frequency shift and of the change in the anharmonicity constant on the vapor-liquid transition. The pressure and temperature dependence of the CH stretching vibration was also studied for liquid chloroform. While the calculated pressure dependence is in good agreement with that observed, only the direction of the temperature dependence is in accordance with experimental observation. I n te r p r e ta tio n o f V a p o r-L iq u id F re q u e n c y S h ift 
  Reference    Z. Naturforsch. 46a, 49—59 (1991); received 
  Published    1991 
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 Identifier    ZNA-1991-46a-0049 
 Volume    46 
9Author    AnthonyM. Popowicz2, Ting-HaiL. Ub, Jacob BigeleisencRequires cookie*
 Title     
 Abstract    e m p e r a tu r e D e p e n d e n c e o f th e L iq u id -V a p o r Is o to p ic F r a c tio n a tio n F a c to r s in C D 3H -C H 4 a n d C D 3F -C H 3F M ix tu r e s * Unserem Kollegen, Herrn Dr. Karl Heinzinger, zum 60. Geburtstag gewidmet The liquid-vapor isotope fractionation factors, LVIFF, a = CD3X/CH3X)j/(CD3X/CH3X)v, of CD3H-CH4 and CD3F CH3F mixtures have been measured from 102 160 K and 182 254 K, respectively. The results are in good agreement with previous vapor pressure ratios, VPIE, which cover the ranges 90 112 K and 132 211 K, respectively. Over the temperature ranges of the LVIFF measurements, lna is negative for the CD3H-CH4 mixture and positive for the CD3F-CH3F mixture. There is significant curvature in a plot of T2 In a vs. T for the CD3H-CH4 mixture. The curvature is related to the densities of the liquid and vapor phases. It is shown that an expansion of the pair correlation function up to powers of the square of the densities of the liquid and vapor phases accounts for the T2 In a vs. T curvature and leads to In a equal to zero at the critical temperature. Correction of the LVIFF values of T2 In a for the density effect gives values for the contributions of translation, rotation and internal vibration in good agreement with previous cell model calculations. Similar treatment of the LVIFF data on the CD3F-CH3F mixture leads to the conclusion that the internal zero point energy effect on the differences in the heats of vaporization of CH3F and CD3F makes a small contribution to the overall difference in free energies of vapor­ ization. 
  Reference    Z. Naturforsch. 46a, 60 (1991); received August 8 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0060 
 Volume    46 
10Author    Läszlö PusztaiRequires cookie*
 Title     
 Abstract    o d e llin g o f P a r t i a l a n d T o ta l R a d ia l D is tr ib u tio n F u n c tio n s o f A m o rp h o u s N i 2B U s in g R e v e rse M o n te C a r lo S im u la tio n The use of Reverse Monte Carlo simulation, a novel method of structural modelling, looks very promising for the case of metallic glasses. In this paper initial results are shown for glassy Ni2B, using experimental radial distribution functions as input information. 
  Reference    Z. Naturforsch. 46a, 69 (1991); received September 3 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0069.pdf 
 Identifier    ZNA-1991-46a-0069 
 Volume    46 
11Author    J. Turner, J. L. Finney, A. K. SoperRequires cookie*
 Title     
 Abstract    e u tro n D if f r a c tio n S tu d ie s o f S t r u c t u r e in A q u e o u s S o lu tio n s o f U r e a a n d T e tra m e th y la m m o n iu m C h lo rid e a n d in M e th a n o l Dedicated to Dr. Karl Heinzinger on the occasion of his 60 th birthday Neutron diffraction measurements on aqueous 2-14 molal urea solutions have been made using nitrogen isotope substitution on the urea and hydrogen isotope substitution on the water. In addition, the hydration region of the tetramethylammonium ion in 2.0 m urea solution has been investigated by nitrogen isotope substitution on the TMA at 0.5 m and 2.0 m concentration of TMAC1. The N-water correlation functions are very similar across the concentration range, and the H-H correlation function in concentrated urea solution is little changed from that of pure water. In the TM AC1 solutions the hydration peak is unchanged by the addition of 2.0 m urea. Thus urea appears to fit into the water network without causing significant perturbation of the average water structure or of the hydration region of another solute. In addition to the study of urea we have also made preliminary measurements to test the feasibility of carbon isotope substitution in liquid methanol. 
  Reference    Z. Naturforsch. 46a, 73—83 (1991); received September 3 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0073.pdf 
 Identifier    ZNA-1991-46a-0073 
 Volume    46 
12Author    T. Yamaguchi, S. Tanaka, H. Wakita, M. Misawa1, I. Okada2, A. K. Soper3, W. S. Howells3Requires cookie*
 Title     
 Abstract    u ls e d N e u tr o n D if fr a c tio n S tu d ie s o n L a n t h a n i d e (I I I) H y d r a tio n in A q u e o u s P e r c h lo r a te S o lu tio n s Dedicated to Dr. Karl Heinzinger on the occasion of his 60th birthday Pulsed neutron diffraction measurements are reported on 2 molar aqueous solutions of Pr3 + , Nd3 + , Tb3 + , Dy3 + , Tm3 + , and Yb3+ in D20 at room temperature. The first order difference technique on isomorphous ions is used to derive the metal ion pair correlation functions in these systems. The metal-oxygen and metal-deuterium distances and the hydration numbers are deter­ mined. The data indicate that the hydration number changes from ~ 10 for the lighter ions to ~8 for the heavier ones in the series. The water dipole is orientated on the average at an angle of 10 ~ 20 degrees to the metal-oxygen vector; these values are significantly smaller than those found for mono-and di-valent ions. The present results are compared with other results from neutron diffraction with isotope substitution, X-ray diffraction, and extended X-ray absorption fine structure. 
  Reference    Z. Naturforsch. 46a, 84—88 (1991); received August 1 1990 
  Published    1991 
  Keywords    Neutron diffraction, Lanthanide(IlI) ions, Ionic hydration Structure Electrolyte solutions 
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 Identifier    ZNA-1991-46a-0084 
 Volume    46 
13Author    D. S. Ludwig, Gill, M. D. ZeidlerRequires cookie*
 Title     
 Abstract    Oxygen-17 enriched methanol CD317OH was synthesized and as well as 170 nmr relaxation rates were measured in the temperature range 180-310 K. By varying the 1 O-content different contributions to the proton relaxation rate could be separated and from the lvO H dipolar interaction contribution the correlation time of the OH bond was determined. These results are compared to recent computer simulation data. Additional deuteron relaxation measurements on CHjOD yielded the quadrupole coupling constant which increases with falling temperature. The 1 O quadrupole coupling constant shows a similar trend with temperature but not as pronounced. M o le c u la r R e o r ie n ta tio n in L iq u id M e th a n o l 
  Reference    Z. Naturforsch. 46a, 89 (1991); received October 19 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0089 
 Volume    46 
14Author    G. Pálinkás, I. BakóRequires cookie*
 Title     
 Abstract    x c e s s P r o p e r tie s o f W a te r -M e th a n o l M ix tu r e s a s S tu d ie d b y M D S im u la tio n s Dedicated to Dr. K. Heinzinger on the occasion of his 60th birthday Molecular dynamics simulations with pair interactions reproduce experimental excess properties of methanol-water mixtures. Water molecules lose, and methanol molecules gain neighbours in the mixtures as compared to the solvents. The water-methanol mixture with 0.25 mole fraction of methanol, resulting in extreme values for different excess properties, is characterized by the highest number of molecules with maximal number of H-bonded neighbours. 
  Reference    Z. Naturforsch. 46a, 95—99 (1991); received November 12 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0095 
 Volume    46 
15Author    G. W. NeilsonRequires cookie*
 Title      
 Abstract    Dedicated to Karl Heinzinger on the occasion of his 60 th birthday. This review compares results of neutron and X-ray diffraction experiments with computer simu­ lation and theoretical calculation for aqueous electrolyte solutions at the atomic level in terms of the partial radial distribution functions of several ionic solutions, and includes results for the ion-water and ion-ion structure of systems containing alkali ions, alkaline earth ions, transition metal cations and a few anions. T h e S t r u c t u r e o f A q u e o u s E le c tro ly te S o lu tio n s : C o m p a ris o n o f C o m p u te r S im u la tio n a n d E x p e r im e n t 
  Reference    Z. Naturforsch. 46a, 100—106 (1991); received April 25 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0100 
 Volume    46 
16Author    V. Notoa, M. Martorana2, S. L. Migliore3, ForniliaRequires cookie*
 Title     
 Abstract    A Monte Carlo simulation of ammonium aqueous solution at infinite dilution shows that this ion is on the average rather loosely bonded to three of the fourteen water molecules present in its first hydration shell. This result agrees with conclusions suggested by recent experiments on the rota­ tional mobility of ammonium in liquid water. H y d r a tio n o f th e A m m o n iu m I o n : M o n te C a r lo S im u la tio n 
  Reference    Z. Naturforsch. 46a, 107 (1991); received August 3 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0107 
 Volume    46 
17Author    Suchada Kheawsrikula, SupotV. Hannongbua, BerndM. RodeRequires cookie*
 Title     
 Abstract    o n te C a rlo S im u la tio n o f M a g n e s iu m Io n in 18.45 m o l% A q u e o u s A m m o n ia S o lu tio n A Monte Carlo simulation has been performed for a magnesium ion in 18.45 mol% aqueous ammonia solution at 20 °C, using additive pairwise potential functions obtained from ab-initio calculations. The structural arrangement of the solvent molecules in the vicinity of the ion is discussed in terms of radial distribution functions and average molecular orientations. It was found that the first solvation shell of the ion consists of four water and three ammonia molecules, and the second shell of nine water and five ammonia molecules. 
  Reference    Z. Naturforsch. 46a, 111—116 (1991); received May 22 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0111 
 Volume    46 
18Author    Sunantha Hengrasmee, MichaelM. ProbstRequires cookie*
 Title      
 Abstract    Dedicated to Dr. Kar! Heinzinger on the occasion of his 60th birthday Hydrated lanthanide(III) ions Ln3 + (H20)8 with Ln3 + = La3 + to Yb3+ have been studied using ab-initio methods. The binding energy as a function of ion-water distance and position of the ion in the rare earth series is discussed. The calculations are related to recent experimental results elucidating the hydration behaviour of lanthanide(III) ions. Since no S-shape behaviour is found for complex binding energies or metal-oxygen distance, the calculations indicate that observed thermo­ dynamic anomalities should come from hydration number changes due to the different ionic radii within the series. The non-additivity of the ion-water interactions has been calculated and it is found that its relative importance increases from 26% for La3+ to 32% for Ln3 + . 
  Reference    Z. Naturforsch. 46a, 117—121 (1991); received October 9 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0117 
 Volume    46 
19Author    E. Hawlicka, R. GrabowskiRequires cookie*
 Title     
 Abstract    h e C o n d u c ta n c e o f N a l a n d T e tra e th y la m m o n iu m Io d id e in M ix t u r e s o f M e th a n o l w ith A c e to n itrile a n d W a te r The conductance of Nal and Et4NI in methanol-acetonitrile and methanol-water mixtures was measured at 25 ± 0.005 °C for the whole range of the solvent compositions, the salt molarity ranging from 5 • 10"5 up to 1 • 10~2. Several equations describing the influence of the salt concentration on the equivalent conductance are examined and the Fuoss-Hsia equation with the Fernandez-Prini parameters is found to be the most appropriate one for systems with weak ionic association. Variations with the solvent composition of the limiting equivalent conductance, the distance be­ tween ions forming ion pairs and the association constant are discussed. Nonmonotonous changes of the association constant are concluded to be a feature of microheterogenous systems. 
  Reference    Z. Naturforsch. 46a, 122—126 (1991); received 23 July 1990 
  Published    1991 
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 Identifier    ZNA-1991-46a-0122 
 Volume    46 
20Author    K. Ibuki, M. NakaharaRequires cookie*
 Title      
 Abstract    Dedicated to Dr. Karl Heinzinger on the occasion of his 60th birthday For heavy water solutions of LiCl, NaCl, KCl and CsCl at 25 and 40 C and KI at 25 °C the values of 5(M +) and ß(X") in the equation r]/rj0= 1 + A |/c + [ß(M +) + ß(X-)] c were determined under the conventional assumption ß(K +) = ß(Cl~). Here rf is the viscosity of the solvent and c the molarity. The solvent isotope effect on the ß values was found to be small. The B values for the medium-sized ions K + , Cs + , Br~, and I" were systematically more negative in heavy water than in light water. This is consistent with the idea that negative B values indicate the ability of the ion to break the structure of the water, the structure of heavy water being more developed than that of light water. For the tetraalkylammonium ions, Me4N + , Pr4N + , and Bu4N + , on the other hand, the solvent isotope effect was small and random irrespective of the ion size. The temperature coefficients of B for the monatomic ions in heavy water were the same as for those in light water. S o lv e n t Is o to p e E ffe c t on th e V is c o sity C o e f fic ie n t B f o r M o n o v a le n t Io n s in W a te r a t 25 a n d 4 0 °C 
  Reference    Z. Naturforsch. 46a, 127—130 (1991); received 30 May 1990 
  Published    1991 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0127.pdf 
 Identifier    ZNA-1991-46a-0127 
 Volume    46 
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