Akm[k_,m_]:=Piecewise[{{(Eappxy + Eappyz + Eapxz + Eapy2 + Eapz2x2)/5, k == 0 && m == 0}, {0, (k != 2 && k != 4) || (k != 4 && m != -2 && m != -1 && m != 0 && m != 1 && m != 2) || (m != -4 && m != -3 && m != -2 && m != -1 && m != 0 && m != 1 && m != 2 && m != 3 && m != 4)}, {(-(Sqrt[6]*Eappyz) + Sqrt[6]*Eapxz - Sqrt[6]*Eapy2 + Sqrt[6]*Eapz2x2 + 2*Sqrt[2]*Mapz2x2y2)/4, k == 2 && (m == -2 || m == 2)}, {(Sqrt[3]*Mappxyyz - 2*Mapy2xz)/Sqrt[2], k == 2 && m == -1}, {(-2*Eappxy + Eappyz + Eapxz - Eapy2 + Eapz2x2 - 2*Sqrt[3]*Mapz2x2y2)/2, k == 2 && m == 0}, {-(Sqrt[3/2]*Mappxyyz) + Sqrt[2]*Mapy2xz, k == 2 && m == 1}, {(-3*Sqrt[7/10]*(4*Eappxy - 3*Eapy2 - Eapz2x2 - 2*Sqrt[3]*Mapz2x2y2))/8, k == 4 && (m == -4 || m == 4)}, {(-3*Sqrt[7/5]*(2*Mappxyyz + Sqrt[3]*Mapy2xz + Mapz2x2xz))/4, k == 4 && m == -3}, {(-3*(4*Eappyz - 4*Eapxz - 3*Eapy2 + 3*Eapz2x2 + 2*Sqrt[3]*Mapz2x2y2))/(4*Sqrt[10]), k == 4 && (m == -2 || m == 2)}, {(-3*(2*Mappxyyz + Sqrt[3]*Mapy2xz - 7*Mapz2x2xz))/(4*Sqrt[5]), k == 4 && m == -1}, {(3*(4*Eappxy - 16*Eappyz - 16*Eapxz + 9*Eapy2 + 19*Eapz2x2 - 10*Sqrt[3]*Mapz2x2y2))/40, k == 4 && m == 0}, {(3*(2*Mappxyyz + Sqrt[3]*Mapy2xz - 7*Mapz2x2xz))/(4*Sqrt[5]), k == 4 && m == 1}}, (3*Sqrt[7/5]*(2*Mappxyyz + Sqrt[3]*Mapy2xz + Mapz2x2xz))/4]