User:Theboyof1990

'TIPS ON AROMATICITY' An aroma compound, also known as odorant, aroma, fragrance or flavor, is a chemical compound that has a smell or odor. A chemical compound has a smell or odor when two conditions are met: the compound needs to be volatile, so it can be transported to the olfactory system in the upper part of the nose, and it needs to be in a sufficiently high concentration to be able to interact with one or more of the olfactory receptors.

Quantum-mechanical screening

In real metals, electrical screening is more complex than described above in the Fermi-Thomas theory. This is because Fermi-Thomas theory assumes that the mobile charges (electrons) can respond at any wave-vector. However, it is not energetically possible for an electron within or on a Fermi surface to respond at wave-vectors shorter than the Fermi wave-vector. This is related to the Gibbs phenomenon, where fourier series for functions that vary rapidly in space are not good approximations unless a very large number of terms in the series are retained. In physics this is known as Friedel oscillations, and applies both to surface and bulk screening. In each case the net electric field does not fall off exponentially in space, but rather as an inverse power law multiplied by a oscillatory term. The area of many-body physics devotes considerable effort to quantum-mechanical screening, which is very relevant to condensed matter physics.--Theboyof1990 (talk) 14:43, 5 November 2008 (UTC)74360783