Fractional charge revealed in computer simulations of resonant tunneling in the fractional quantum Hall regime.

The concept of fractional charge is central to the theory of the fractional quantum Hall effect. Here I use exact diagonalization as well as configuration space renormalization to study finite clusters which are large enough to contain two independent edges. I analyze the conditions of resonant tunneling between the two edges.

Polarization forces in water deduced from single molecule data.

The intermolecular electrostatic and polarization interactions in water are determined using a minimal atomic multipole model constructed with distributed polarizabilities. Hydrogen bonding and other properties of water-water interactions are reproduced by only three multipoles mu(H), mu(O), and theta(O) and two polarizabilities alpha(O) and alpha(H), which characterize a single water molecule and are deduced from single-molecule data.

Rules for minimal atomic multipole expansion of molecular fields.

A nonempirical minimal atomic multipole expansion (MAME) defines atomic charges or higher multipoles that reproduce electrostatic potential outside molecules. MAME eliminates problems associated with redundancy and with statistical sampling, and produces atomic multipoles in line with chemical intuition.