with n = (n x , n y , n z ), and k = (k x , k y , k z ) being real and reciprocal lattice vectors with n i = L i m i and k i = 2π • m i /L i , based on integer numbers for m i . Here, we use n = |n| and k 2 = |k| 2 , while α represents the Ewald convergence parameter. The exact size of α does not really matter, but it affects the convergence of the sums in Equation . In Ref.