This paper presents a simple and efficient equation of state which can be used for quick and accurate computing of the thermodynamic functions of partly ionized and weakly coupled plasmas. Based on the free energy minimization method, the improvement of the equation of state includes a detailed account of the physical processes of non-ideal effects consisting of electron degeneracy, Coulomb cou...

The rigidity and stability of the tertiary structure of yeast tRNAPhe is related to a bond index obtained in an IEHT (iterative extended Hückel theory) calculation. The index permits a quantitative estimate of the electron density along the hydrogen bond, having thus an appealing physical meaning. The results indicate that Hoogsteen-type bonds have, as expected, greater electronic population th...

Two overall neutral surfaces with positively and negatively charged domains ("patches") have been shown in recent experiments to exhibit long-range attraction when immersed in an ionic solution. Motivated by the experiments, we calculate analytically the osmotic pressure between such surfaces within the Poisson-Boltzmann framework, using a variational principle for the surface-averaged free ene...

Dense suspensions of small strongly interacting particles are complex systems, which are rarely understood on the microscopic level. We investigate properties of dense suspensions and sediments of small spherical Al2O3 particles in a shear cell by means of a combined Molecular Dynamics (MD) and Stochastic Rotation Dynamics (SRD) simulation. We study structuring effects and the dependence of the...

The electronic and structural possibilities of a recently conceived, as-yet unsynthesized, AM6E8 (or A2M6E8) structural type are explored. With A an alkaline earth metal, M a transition metal, and E a main group element, a range of geometries containing M–M pairs with very short separations is feasible. Density functional theory geometry optimizations and an extended Hückel analysis of the bond...

Let G be a finite connected simple graph and μ(G) be the Mycielskian of G. We show that for connected graphs G and H, μ(G) is isomorphic to μ(H) if and only if G is isomorphic to H. Furthermore, we determine the energy of the Mycielskian of a connected regular graph G in terms of the energy E(G) of G, where the energy of G is the sum of the absolute values of the eigenvalues of G. The energy of...

We investigate theoretically polyelectrolyte bridging interactions on the two-body level. The model system is composed of two macroions with two oppositely charged flexible chains. The electrostatic interactions are treated on the Debye Hückel level. The formal level of the theory is provided by the Feynman-Kleinert variational method generalized to include also self-interactions between polyel...

We show that the precise orientation of a C(60) molecule which terminates the tip of a scanning probe microscope can be determined with atomic precision from submolecular contrast images of the fullerene cage. A comparison of experimental scanning tunneling microscopy data with images simulated using computationally inexpensive Hückel theory provides a robust method of identifying molecular rot...

In this work, we consider a lattice-gas model of charge regulation with electrostatic interactions within the Debye–Hückel level approximation. addition to long-range interactions, incorporates nearest-neighbor for representing non-electrostatic forces between adsorbed ions. The Frumkin–Fowler–Guggenheim isotherm obtained from mean-field analysis accurately reproduces simulation data points.

The statistical mechanical approach to Casimir problems for dielectrics separated by a vacuum gap turns out to be compact and effective. A central ingredient of this method is the effect of interacting fluctuating dipole moments of the polarizable particles. At arbitrary temperature the path-integral formulation of quantized particles, developed by Høye-Stell and others, is needed. At high temp...