Case of $T_d$ group

In the case of the $T_d$ group, the best way to exploit symmetry is to put the vertices of the tetrahedron at the vertices of a cube like in the following example:

C 1 (CENTRE 1) 0.98523954 0.98523954 0.98523954 CHARGE = 6.0
C 2 (CENTRE 2) -0.98523954 -0.98523954 0.98523954 CHARGE = 6.0
C 3 (CENTRE 3) -0.98523954 0.98523954 -0.98523954 CHARGE = 6.0
C 4 (CENTRE 4) 0.98523954 -0.98523954 -0.98523954 CHARGE = 6.0

The input for grid09 corresponds to a qurter of a cube, i.e.:

0.05 0.05 -7.25
7.20 7.20 14.5

Then run top_sym with two C₂ rotation, one around the x axis, the other around y:

tetrahedrane_ebas.sbf 2
C2X
0.0 0.0 0.0
C2Y
0.0 0.0 0.0