Akm[k_,m_]:=Piecewise[{{(Eagx2y2 + Eagz2 + Eb1g + Eb2g + Eb3g)/5, k == 0 && m == 0}, {(Sqrt[6]*Eb2g - Sqrt[6]*Eb3g - 4*Sqrt[2]*Mag)/4, k == 2 && (m == -2 || m == 2)}, {(-2*Eagx2y2 + 2*Eagz2 - 2*Eb1g + Eb2g + Eb3g)/2, k == 2 && m == 0}, {(3*Sqrt[7/10]*(Eagx2y2 - Eb1g))/2, k == 4 && (m == -4 || m == 4)}, {(3*(Eb2g - Eb3g + Sqrt[3]*Mag))/Sqrt[10], k == 4 && (m == -2 || m == 2)}, {(3*(Eagx2y2 + 6*Eagz2 + Eb1g - 4*Eb2g - 4*Eb3g))/10, k == 4 && m == 0}}, 0]