private void rescaleVelocities(float ratio) {
		synchronized (forceCalculator) {
			Atom a = null;
			for (int i = 0; i < iAtom; i++) {
				a = atom[i];
				if (!a.isMovable())
					continue;
				a.vx *= ratio;
				a.vy *= ratio;
				a.vz *= ratio;
			}
		}
	}