Configuration spaces of hard spheres

Total energy calculations of three- and four-atomic silver clusters have been performed by the spin-polarized version of the CNDO/2 method to get the most stable equilibrium geometries, atomization energies, and charge and spin distribution on the atoms for three different basis sets: {s}, {sp}, and {spd}. When viewed from the equilateral triangle and square geometries, the last electronic configuration, i.e. the {spd} one, appears to be most stable with respect to the geometrical deformations considered. In this case, the behaviour of the atoms of both clusters resembles that of hard spheres (i.e. close-packing).

Download Full-text

Excess entropy of the systems of molecules differing in size and shape

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19830192 ◽

1983 ◽

Vol 48 (1) ◽

pp. 192-198 ◽

Cited By ~ 5

Author(s):

Tomáš Boublík

Keyword(s):

Equation Of State ◽

Hard Spheres ◽

Excess Entropy ◽

Convex Bodies ◽

Pure Substance ◽

Liquid Equilibrium ◽

Simple Rules ◽

Different Shapes ◽

The Mean

The excess entropy of mixing of mixtures of hard spheres and spherocylinders is determined from an equation of state of hard convex bodies. The obtained dependence of excess entropy on composition was used to find the accuracy of determining ΔSE from relations employed for the correlation and prediction of vapour-liquid equilibrium. Simple rules were proposed for establishing the mean parameter of nonsphericity for mixtures of hard bodies of different shapes allowing to describe the P-V-T behaviour of solutions in terms of the equation of state fo pure substance. The determination of ΔSE by means of these rules is discussed.

Download Full-text

Study of Sedimentation Velocity of Block Copolymer Micelles

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19930071 ◽

1993 ◽

Vol 58 (1) ◽

pp. 71-76 ◽

Cited By ~ 3

Author(s):

Minmin Tian ◽

C. Ramireddy ◽

Stephen E. Webber ◽

Petr Munk

Keyword(s):

Block Copolymer ◽

Methacrylic Acid ◽

Mixed Solvent ◽

Hard Spheres ◽

Sedimentation Velocity ◽

Hydrodynamic Coefficient ◽

Block Copolymer Micelles ◽

Copolymer Micelles ◽

Size Heterogeneity ◽

Good Agreement

No anomalies were observed during the measurement of sedimentation coefficients of block copolymer micelles formed by copolymers of styrene and methacrylic acid in a mixed solvent; 80 vol.% of dioxane and 20 vol.% of water. The shapes of the sedimenting boundaries suggest that the size heterogeneity of the micelles is small. Linear relations between 1/s and c were obtained. The value of the hydrodynamic coefficient κ was between 2 and 4 in a good agreement with the value 2.75 or 2.86 that was obtained by combining Burgers' or Fixman's values of the coefficient of the concentration dependence kvs for hard spheres with Einstein's value of [η] for spheres.

Download Full-text