Common methods of determining atomic polarizabilities suffer from the inclusion of nonlocal effects such as charge polarization. A new method is described for determining fully ab initio atomic polarizabilities based on calculating the response of atomic multipoles to the local electrostatic potential. The localized atomic polarizabilities are then used to calculate induction energies that are ...

Molecular dynamics is of fundamental interest in natural science research. The capability of investigating molecular dynamics is one of the various motivations for ultrafast optics. We present our investigation of photoionization and nuclear dynamics in methyl iodine (CH3I) molecule with an X-ray pump X-ray probe scheme. The pump–probe experiment was realized with a two-mirror X-ray split and d...

The variations of the electrical conductivity with temperature and electric field of the ternary alloy of gallium, aluminium and arsenic (Al0.75Ga0.25As) with atomic compositions of 99/1 and 98/2 have been investigated. The electrical conductivity of the alloy increases with temperature according to the relation, ? = ?0 exp (??/kT). The activation energy calculated from this empirical relation ...

A method is presented for extending any bond-order potential (BOP) to include charge transfer between atoms through a modification of the split-charge equilibration (SQE) formalism. Variable limits on the maximum allowed charge transfer between atomic pairs are defined by mapping bond order to an amount of shared charge in each bond. Charge transfer is interpreted as an asymmetry in how the sha...

The charge distribution in atoms with closed electron shells is spherically symmetric, whereas atoms with partially filled shells can form covalent bonds with pointed lobes of increased charge density. Covalent bonding in the bulk can also affect surface atoms, leading to four tiny humps spaced by less than 100 picometers in the charge density of adatoms on a (001) tungsten surface. We imaged t...

In this study, we have mapped the surface charge of wool fibers using chemically specific high-resolution force spectroscopy in order to better understand the dispersion of amino acids in relation to fiber morphology. The inter-surface forces between standard atomic force microscopy (AFM) probe tips (tip radius ~ 50 nm) functionalized with COOH and NH(3) terminated alkanethiol self assembling m...

Low-energy spin and charge excitations of one-dimensional interacting fermions are completely decoupled and propagate with different velocities. These modes, however, can decay due to several possible mechanisms. In this Letter we expose a new facet of spin-charge separation: not only the speeds but also the damping rates of spin and charge excitations are different. While the propagation of lo...

In this Report we show the role of charge defects in the context of the formation of electrostatically defined quantum dots. We introduce a barrier array structure to probe defects at multiple locations in a single device. We measure samples both before and after an annealing process which uses an Al2O3 overlayer, grown by atomic layer deposition. After passivation of the majority of charge def...

In the present work, the structural and electronic properties, and conductivity of (5,5) and (6,6) Single Walled Carbon Nanotubes in the ground state have done by using the Hartree-Fock and density functional theory DFT-B3LYP/6-31G* level. Delocalization of charge density between the bonding or lone pair and antibonding orbitals calculated by NBO (natural bond orbital) analysis. These methods a...