"f" . "Packing Fraction"@en . "The \"Packing Fraction\" is the fraction of volume in a crystal structure that is occupied by atoms." . "http://www.iso.org/iso/catalogue_detail?csnumber=31895"^^ . "http://en.wikipedia.org/wiki/Atomic_packing_factor"^^ . . "\\(f = \\frac{\\Delta_r}{A}\\), where \\(\\Delta_r\\) is the relative mass excess and \\(A\\) is the nucleon number."^^ . . . .