Symmetry Pages

Symmetry example: water

Symmetry Pages

The water molecule possesses three symmetry operations in addition to the identify. These are illustrated below. The principal symmetry axis is the rotational axis, which we designate as the z direction. The rotation axis is along the intersection of the two mirror planes. There is no symmetry specification for which mirror plane is in the xz and yz planes. This may lead to ambiguity in the assignment of irreducible represnetations where the symmetry planes are poorly defined.



To identify the point group symmetry of the water molecule, we first identify all possible symmetry operations. There are four (those shown here plus an identity operation). By using a symmetry idenification flow chart, or by examining the common point groups of molecules, we can identify these four operations with the C2v point group.

We shall now sequence through the valence molecular orbitals (ie not including the 1s orbitals on the oxygen atom).

Water molecule index.
First molecular orbital.

Revised: © University of Newcastle upon Tyne, UK