PE Card

On the Home tab, in the Planes / arrays group, click the  Periodic boundary icon. From the drop-down list, click the  Periodic boundary (PE) icon.

Figure 1. The PE - Specify a periodic boundary condition dialog - One dimension

Figure 2. The PE - Specify a periodic boundary condition dialog - Two dimensions

Parameters:

One dimension

One dimensional periodicity is used when the unit cell is repeated along a line. The unit cell definition is displayed in the dialog above depicting the One dimension option.

Two dimensions

Two dimensional periodicity is used when the unit cell is repeated to form a surface. The unit cell definition is displayed in the dialog above depicting the Two dimensions option.

S1

Name of the point S1.

S2

Name of the point S2.

S3

Name of the point S3. (Only required for two dimensional periodicity.)

The lattice vectors ( ${\widehat{u}}_1$ and ${\widehat{u}}_2$ ) do not have to be orthogonal. Geometry may also cross the periodic boundary as long as it lines up with the geometry edge on the opposite side of the unit cell. These features allow a large number of problems to be solved.