code: private void refineReferenceVector() {
  		referenceVector = new Vector3d(Y_AXIS);
  		if (rotationGroup.getPointGroup().startsWith("C")) {
  			referenceVector = getReferenceAxisCylicWithSubunitAlignment();
  		} else if (rotationGroup.getPointGroup().startsWith("D")) {
  			referenceVector = getReferenceAxisDihedralWithSubunitAlignment();
  		}
  
  		referenceVector = orthogonalize(principalRotationVector, referenceVector);
  	}
docs: Returns a normalized vector that represents a minor rotation axis, except
  for Cn, this represents an axis orthogonal to the principal axis.
  @return minor rotation axis