Akm[k_,m_]:=Piecewise[{{(Eapp + Eapx + Eapz)/3, k == 0 && m == 0}, {0, k != 2 || (m != -2 && m != -1 && m != 0 && m != 1 && m != 2)}, {(-5*(Eapp - Eapx))/(2*Sqrt[6]), k == 2 && (m == -2 || m == 2)}, {(5*Mapzx)/Sqrt[6], k == 2 && m == -1}, {(-5*(Eapp + Eapx - 2*Eapz))/6, k == 2 && m == 0}}, (-5*Mapzx)/Sqrt[6]]