public Point3f getCenterOfAtoms() {
		Point3f p = new Point3f();
		if (iAtom <= 0)
			return p;
		for (int i = 0; i < iAtom; i++) {
			p.x += atom[i].rx;
			p.y += atom[i].ry;
			p.z += atom[i].rz;
		}
		float inverse = 1.0f / iAtom;
		p.x *= inverse;
		p.y *= inverse;
		p.z *= inverse;
		return p;
	}