Science Fair Project Encyclopedia

Science Fair Project Encyclopedia Contents Page

Categories: Units of measure | Atomic physics

Atomic units

Atomic units(au) are a convenient system of units of measurement used in atomic physics, particularly for describing the properties of electrons. The atomic units have been chosen such that the fundamental electron properties are all equal to one atomic unit.

The atomic units are:

length: the Bohr radius

a 0

mass: the electron rest mass

m e

charge: the elementary charge

e

energy: the Hartree energy

E h

angular momentum: the Dirac constant $\hbar$

The use of atomic units also simplifies the Schrödinger equation. For example the Hamiltonian for an electron in the hydrogen atom would be:

in SI units:

$\hat H ={{{-\hbar^2} \over {2 m_e}}\nabla^2} + {1 \over {4 \pi \epsilon_0}}{{-e^2} \over {r}}$

in atomic units:

$\hat H ={{{-1} \over {2}}\nabla^2} + {{-1} \over {r}}$

Categories: Units of measure | Atomic physics

Science Fair Project Encyclopedia Contents Page

10-26-2009 08:16:03
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details

All Science Fair Projects

Science Fair Project Encyclopedia for Schools!

Science Fair Project Encyclopedia

Atomic units