ZIB

1

Digitale Medien

Singularities in the consistent hypernetted chain approximation (1994)

Ferreira, P. G. ; Carvalho, R. L. ; Telo da Gama, M. M. ; [weitere]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 101 (1994), S. 594-602

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: We use the consistent set of hypernetted chain (HNC) equations to investigate the stability of liquid and vapor phases of simple fluids. We calculate the phase diagram and discuss the physical (spinodal) and mathematical (termination line) singularities of the theory. The latter delimits a region where the HNC equations have no physically acceptable solutions. Additionally, we confirm that the physical solutions of the HNC equation correspond to local minima of the consistent grand potential which, however, appears to be unbounded from below.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.468115

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2

Digitale Medien

Copolymer brushes (1996)

Ferreira, P. G. ; Leibler, L.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 105 (1996), S. 9362-9370

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: We study a diblock AB copolymer brush in good solvent using the self-consistent field approximation. The copolymer chains of the brush are end grafted to a planar surface always by the same type of monomers. Depending on the Flory–Huggins interaction parameter χAB, we found two different regimes. If χAB(approximately-greater-than)0 a demixing transition occurs when the solvent is poor. An exclusion zone appears close to the grafting surface from where one type of monomers is expelled. In this region a steplike brush is formed by the other monomers. At the extremity of this brush appears then a conventional parabolic brush formed by the excluded monomers. If χAB〈0 the monomers are miscible and backwards twisted configurations become very important as |χAB| increases. For larger values of |χAB| the collapse of the system may occur. © 1996 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.472725

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3

Digitale Medien

The hard ellipse liquid: An integral equation study (1991)

Ferreira, P. G. ; Perera, A. ; Moreau, M. ; [weitere]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 95 (1991), S. 7591-7602

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: We investigate the structural and thermodynamic properties of the isotropic phase of the hard ellipse liquid for several length-to-breadth ratios (2,4,6), using the hypernetted chain (HNC) and Percus–Yevick (PY) integral equation theories. A comparison with the recent simulations of Cuesta and Frenkel [Phys. Rev. A 42, 2126 (1990)] is made. Satisfactory agreement is found with PY theory for small aspect ratios, while for larger ones, HNC results become superior. In addition, HNC (but not PY) predicts the orientational instability of the isotropic phase at a finite density for systems of aspect ratios 4 and 6, in good agreement with computer simulation results. In order to investigate the order of the orientational phase transition, density functional theories (DFT) calculations are carried out using as input the direct correlation functions of the isotropic liquid obtained in this work. No first-order transition is found within the version of DFT used herein.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.461385

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4

Digitale Medien

Thermodynamic consistency in the hypernetted chain theory (1993)

Schlijper, A. G. ; Telo da Gama, M. M. ; Ferreira, P. G.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 98 (1993), S. 1534-1538

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ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: An extended version of the hypernetted chain equation is presented. It allows for fluid inhomogeneity and for three-body interactions. Consistent expressions for thermodynamic functions are given. It is argued that thermodynamic consistency holds even though statistical mechanical relationships are not obeyed. Singularities in the hypernetted chain equation, related to loss of convexity of the associated free energy functional, prevent a complete description of liquid/vapor coexistence in a Lennard-Jones fluid.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.464269

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5

Digitale Medien

A flat Universe from high-resolution maps of the cosmic microwave background radiation (2000)

Ade, P. A. R. ; Bock, J. J. ; Bond, J. R. ; [weitere]

[s.l.] : Macmillian Magazines Ltd.

Nature 404 (2000), S. 955-959

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ISSN: 1476-4687

Quelle: Nature Archives 1869 - 2009

Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik

Notizen: [Auszug] The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic microwave background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small ...

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1038/35010035

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