Packing fraction is defined as a way of expressing the variation of isotopic mass from whole mass number (atomic mass). This fraction can have positive or can have negative sign. A positive packing fraction describes a tendency towards instability.
The equation for packing fraction is: Packing fraction = (N atoms) x (V atom) / V unit cell. N atoms is the number of atoms in a unit cell. V atom is the volume of the atom, and V unit cell is the volume of a unit cell. Substitute the number of atoms per unit cell into the equation.
