I think the lowest energy would be alpha>0 and orientation of the dumbbell is parallel to the z axis.
Then when alpha is zero the direction of the dumbbell is not important,because we will not have quadrupole moment.
And when we have alpha<0 then the lowest energy will be,when we will gave dumbbell perpendicular to the z axis.
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This topic was modified 3 years, 1 month ago by
akarpavi.