Charge optimization is an essential element of rational drug design; given ligand and receptor proteins, one wishes to determine the ligand charge distribution—a vector of partial atomic charges—that maximizes the favorable change in electrostatic free energy on binding. Work in biophysics has shown that this problem is convex, and that it can be solved using standard quadratic programming meth...

There are four fundamental atomic particles-the proton, the neutron, the electron, and the positron. The proton has mass and a unit positive electrical charge. The neutron has mass and no charge. The electron has very small mass compared with the proton and neutron, and has unit negative electrical charge. The positron is the positively charged counterpart of the electron, having equal mass and...

TaN films with different N2 partial pressure were deposited on 304 stainless steel using the magnetron sputtering method. The effect of gas pressure on the mechanical property, morphology and phase structure of the films is investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), microhardness testing, friction coefficient measurements, and wear mechanism study. The XRD results c...

This paper investigates the use of partial replication in the Database State Machine approach introduced earlier for fully replicated databases. It builds on the order and atomicity properties of group communication primitives to achieve strong consistency and proposes two new abstractions: Resilient Atomic Commit and Fast Atomic Broadcast. Even with atomic broadcast, partial replication requir...

Charge density studies utilise a multipolar expansion of the atomic density (and the associated atomic scattering factor) in order to model asphericity. Contributions of the individual multipoles to the atomic density are then refined as multipole population coefficients. Refinement of these coefficients pertaining to odd-order multipoles that are invariant under the crystal point-group symmetr...

The concept of the atomic charge is extensively used to model the electrostatic properties of proteins. Atomic charges are not only the basis for the electrostatic energy term in biomolecular force fields but are also derived from quantum mechanical computations on protein fragments to get more insight into their electronic structure. Unfortunately there are many atomic charge schemes which lea...

A new molecular dynamics model in which the point charges on atomic sites are allowed to fluctuate in response to the environment is developed and applied to water. The idea for treating charges as variables is based on the concept of electronegativity equalization according to which: (a) the electronegativity of an atomic site is dependent on the atom’s type and charge and is perturbed by the ...