private void setElementField(String str1, String str2, double x) {
		if (!(model instanceof MolecularModel))
			return;
		MolecularModel m = (MolecularModel) model;
		int lb = str1.indexOf("[");
		int rb = str1.indexOf("]");
		double z = parseMathExpression(str1.substring(lb + 1, rb));
		if (Double.isNaN(z))
			return;
		int i = (int) Math.round(z);
		if (i >= Element.NMAX || i < 0) {
			out(ScriptEvent.FAILED, "Element " + i + " doesn't exisit.");
			return;
		}
		String s = str2.toLowerCase().intern();
		boolean b = true;
		if (s == "mass")
			m.getElement(i).setMass(x / M_CONVERTER);
		else if (s == "sigma")
			m.getElement(i).setSigma(x * IR_CONVERTER);
		else if (s == "epsilon")
			m.getElement(i).setEpsilon(x);
		else {
			out(ScriptEvent.FAILED, "Cannot set property: " + str2);
			b = false;
		}
		if (b)
			notifyChange();
	}