private void addFictitiousInterval() {
        if (intervals.size() == 0) {
            throw new IndexOutOfBoundsException("There must be at least one interval to add fictitious one");
        }
        // TODO take mass of the QWs for the fictitious layer
        // intervals.add(0, new MatterInterval(0, 0, 0,
        // intervals.get(0).getMass(), intervals.get(0)
        // .getDiel()));
        intervals.add(0, new MatterInterval(0, 0, 0, intervals.get(0).getMass(), intervals.get(0).getDiel()));
        // intervals.add(0, new
        // MatterInterval(-intervals.get(0).getWidth(), 0, 0,
        // intervals.get(0).getMass(), intervals.get(0).getDiel()));
        getFictitiousInterval().setLabel("Fictitious");
        fictitiousRegionReady = true;
    }