MAXRD SYMBOL
InterplanarSpacing

InterplanarSpacing[crystal,{h,k,l}]
calculates the distance between planes with Miller indices hkl using the lattice parameters of crystal.
InterplanarSpacing[crystal,{{h1,k1,l1},…,{hn,kn,ln}}]
calculates the distance between planes with Miller indices hkli using the lattice parameters of crystal.