2 Different Types of Bonds 7 2.1 Covalent Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2 Ionic Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.2.1 Madelung Sums . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.3 Metallic Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.4 Van der Waals Bonds . . . . . . . . . . . ....

The derivation of the van der Waals parameters for the aliphatic CH united atoms of the GROMOS96 force field is presented. The parameters n have been adjusted to reproduce the experimental enthalpies of vaporization and vapor pressures or densities of a set of nine alkanes in the liquid state at 298 Ž . K or at the boiling point in the case of methane , using a cutoff radius for the van der Waa...

We study the dependence of the heat transfer and the van der Waals friction between two semi-infinite solids on the dielectric properties of the bodies. We show that the heat transfer and van der Waals friction at short separation between the solids may increase by many orders of magnitude when the surfaces are covered by adsorbates, or can support low-frequency surface plasmons. In this case t...

The adhesion force due to capillary interaction between two hydrophilic surfaces is strongly dependent on the partial pressure of water and is often calculated using the Kelvin equation. The validity of the Kelvin equation is questionable at low relative humidity (RH) of water, like in high vacuum and dry nitrogen environments, where water is only present as layers of several molecules thick at...

The robotic manipulation of microscopic objects is disturbed directly by the adhesion between the endeffector and the objects. In the microscale, no reliable model of adhesion is available and currently the behaviour of the micro-objects cannot be predicted before experiments. This paper proposes a new model of adhesion based on the analytical resolution of the coupling between the mechanical d...

The van der Waals equation of state for imperfect gases is applied to solutions of macromolecules, especially to explain the fluid-fluid phase transition in protein solutions, a phenomenon of much interest in relation to protein crystallization. The van der Waals b parameter corresponds to the total excluded volume per pair of molecules and can be calculated from independently known molecular p...

Multi-walled hollow nanoparticles made from tungsten disulphide (WS2) show exceptional tribological performance as additives to liquid lubricants due to effective transfer of low shear strength material onto the sliding surfaces. Using a scaling approach based on continuum elasticity theory for shells and pairwise summation of van der Waals interactions, we show that van der Waals interactions ...

A recently proposed general density functional for asymptotic van der Waals forces is used to calculate van der Waals coefficients and reference-plane positions for realistic low-indexed Al surfaces. Results are given for a number of atoms and molecules outside the surfaces, as well as for the interaction between the surfaces themselves. The densities and static image-plane positions that are n...

The interaction between charged particles via the Coulomb interaction is one of the most important features in physics and is familiar to any student of the subject. The way in which electrons and protons bind to form the hydrogen atom is also well known and is a staple of any quantum mechanics course. However, less familiar is the interaction between such bound systems at separation R, which i...

We propose a theoretical novel homodimer model of the β- adrenergic receptor (βAR) in complex with a heterogeneous mixture of free fatty acids (FFAs) and cholesterol based on first-principles calculations. We used the density-functional-based tight binding with dispersion (DFTB-D) method, which accurately evaluates van der Waals interactions between FFAs and amino acid residues in the receptor....