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Rhombic dodecahedral boundaries (IMCON=5)

This is another unusual MD cell (see figure), but which possesses similar advantages to the truncated octahedron, but with a slightly greater efficiency in its use of the cell volume (the ratio is about 74% to 68%).

The principal axis in the X-direction of the rhombic dodecahedron passes through the centre of the cell and the centre of a rhombic face. The Y-axis does likewise, but is set at 90 degrees to the X-axis. The Z-axis completes the orthonormal set and passes through a vertex where four faces meet. If the width D of the cell is defined as the perpendicular distance between two opposite faces, the cell vectors required for the DL_POLY_2 CONFIG file are: (D,0,0), (0,D,0), (0,0,D).These also define the enscribing orthorhombic cell, which has twice the MD cell volume. In DL_POLY_2 the centre of the cell is also the origin of the atomic coordinates.

The rhombic dodecahedron can be used with the Ewald summation method.

The rhombic dodecahedral MD cell.

Next: Slab boundary conditions (IMCON=6) Up: Introduction Previous: Truncated octahedral boundaries (IMCON=4)   Contents   Index